I mean, while there were many DM's I played with in the TSR era who believed in never giving players and even break and were even proud when they slew a PC, the ones whose campaigns lasted the longest did, in fact, softball quite a bit, though I didn't realize that at the time.
Everyone is going to warp the game into what they feel it should be, to become the best game for them (and, hopefully) their players. If the base game isn't brutal enough, it can be made that way. If the game is too brutal, there are things you can do to make it less.
A repeated statement I've heard a lot of from DM's who want the game to be harder is that they feel they are being done a disservice when the game is presented as being less difficult. They cry out that multiclassing should be optional, that characters should have less abilities, should advance slower, should have a more difficult time carrying gear and finding food and shelter. Combats should be riskier, rewards should be lessened, success should be based more on the player being smart than the abilities of the character.
And when the rules present a game that is anything but this, they'll complain that players will feel "entitled" to those things that they don't care for.
I've always found that interesting- I think every DM I've ever encountered has their own house rules. Some have pages and pages of them, all designed to improve the play experience. But apparently, the ability to mod the game isn't enough- the game must be written to, if not fully support their vision of the game, then contain nothing that contradicts it.
Now often in discussions, DM's will state "the way I play is enjoyed by all the people I play with", as if there exists no other possible paradigm. Which begs the question- if this is so, then who are these players who feel "entitled" to things in the rulebooks? If there were no dissenting opinions, it feels like there wouldn't be a problem, no?
But let's set that aside. I'm assuming the real problem here is getting new blood into games. A DM who has been running games and campaigns for ten, twenty, thirty, forty, or even more years knows pretty much what they like. They know what power level feels appropriate for their vision of "D&D". They don't need a new edition. They don't need the "approval" of any game company. They may have accumulated so many house rules that the rulebooks themselves are peripheral to the experience.
But what happens if you need new players (or even a new DM)? The old group broke up, people are too busy adulting, you've moved to a new area- whatever the reasons, you find yourself at the FLGS looking for new blood. You mention that you play D&D, and these new faces light up. Maybe they've always wanted to play, or they heard about it. Maybe they watch Critical Role. Maybe they've played BG3. Maybe they're even playing D&D, with these flashy new rulebooks with sometimes questionable art.
What they are expecting might be very different than the game you love. They might insist on playing this new game- the books are in the stores, after all, easily acquired. They may already own them! And surely, the newest version of the game, after 50 years of existence, has to be good, right?
So you may find yourself forced to interact with this strange new beast. Maybe you embrace it. Maybe you reject it. Mostly, I imagine you're somewhere in the middle. But hey, gaming is gaming, and D&D is D&D...right?
I don't know where the cracks start to appear. Maybe someone wants to play a Drow and is confused when you describe their evil, demon-worshiping matriarchy and how NPC's will revile and fear their character. Or they want to be a Dragon-man or a walking golem. Maybe someone wants to multiclass, or the "variant Human" Fighter takes Heavy Armor Mastery and laughs at the pitiful attacks of goblins. Maybe it happens when the Bear Totem Barbarian or Moon Druid wades into a pile of foes and emerges victorious, ready for more encounters. Or when characters go down and are instantly revived.
Maybe it happens when you realize that every game day must be chock full of encounters or the party can go all out and turn combats into cakewalks. Maybe it happens when you're grueling adventure in the tropics or a desert is upended by Goodberry or Tiny Hut. Maybe it happens when the party starts gaining new and strange abilities faster than you can keep up.
Maybe the group finds a tactic that requires specialized tactics and foes to foil, and you can't just run the monsters out of an adventure and hope to do anything to the party of three Clerics using Spirit Guardians.
There's a thousand ways things can go awry. This isn't the D&D you remember or love. This is some new abomination that seems designed to be incompatible with older style adventures. You tried to run White Plume Mountain and 95% of the adventure was a cakewalk. The exploration and puzzles fell flat, the combat encounters had too few foes in small, confined spaces. You tried throwing infinite Efreeti at the players, but either gave up in frustration, or just TPK'd the party, and now your players look super annoyed.
It sucks. And if you try to reach out to other people playing the game, you might get some helpful advice. Or you get answers like: "You're playing the game wrong. This is what the game is now. I've been playing for ten thousand years and I've never had any of these problems you're talking about- I don't think they exist. It's a skill issue. Go watch these YouTube videos."
This sucks as well.
Then a new...edition? Version? Update? of the game is announced. There's surveys. Maybe you took part in them and discussions. Maybe you didn't. But either way, suddenly people are excited about all the upgrades.
And you take one look at it, and all you see is the game veering even further from that thing you love. And when you try to explain what you feel has gone horribly, horribly wrong, you get some people who nod in agreement. And some who don't, saying "who wants to play a game like that?".
I don't really know how to end this post. I'd like to offer hope, but I don't really have any. I play 5e, but I'd be much happier playing some other version of D&D, or even another fantasy TTRPG entirely. But this is what everyone wants to play. I care for 5.2024e or whatever we're calling it even less- there's one or two things I go "oh, that's neat", but a lot of the positive changes were things we're already doing. Nothing makes me want to buy new books.
The other DM in my group is a Kobold Press fanboy with a ton of their products, and he wants to move us into Tales of the Valiant. I'm looking at it going "it's just more of the same". So I'm pretty neutral about it. I don't have to pay WotC money is the main draw, lol.
I don't see D&D going back to forms I loved best. I don't really see it ever taking on a form that everyone will be happy about- profits drive the business, and so whatever keeps the lights on is going to be sold to us. Whether that means a game of anime-style superheroes or one of gritty murderhobos just trying to survive in a harsh, cruel world. Or someplace between those extremes.
It's impossible to really sort D&D fans into any kind of group or factions- we each have things we like. There are the innovators, who want to see new ideas and concepts. They may have really enjoyed the tail end of TSR and the WotC era. Maybe to them, the heyday was late 3.5 or pre-Essentials 4e, where new ideas abounded, and it was more about setpiece battles and encounter-based resources.
There are some among the old guard, who want magic to feel rare and special, who want their game to hew closer to reality than fantasy, who want people worrying about torches and rations and getting lost. Who like their Wizards throwing darts and hiding behind the front line, with the occasional big spell tossed out to win an engagement.
But there are also older players who had 36th-level characters who advanced to become Immortals, each festooned with artifacts, who travel the planes and hobnob with deities- and maybe even killed one or two.
Newer players may not have gotten inspiration from pulp heroes or low fantasy. They may not know who Elric is or what the heck is Thieves' World anyways? They want to play characters like The Witcher or Harry Potter, or Random Isekai Protagonist #38, who have special powers and rarely have to worry about not being able to use them.
You'll note the current D&D isn't really a good fit for any of these, not really. And it never really has- even in it's oldest iterations, you had people pulling in different directions. And the game never 100% supported one over the other.
Group A that struggled to hit level 5 over the course of months, losing many characters along the way, who were just now fortunate enough to find a +1 Bec de Corbin that nobody is proficient in was having a blast carefully plotting out how many porters they would need to hire to carry the loot out of a conquered dungeon.
While at the same time, Group B has just hit level 7 in one month's time in universe while exploring the Ruins of Undermountain, with everyone having multiple magic items, enough potions of healing to float a battleship, and are carrying thousands of gold pieces in Bags of Holding while taking a break to use their artifact that casts Create Food and Water 3/day while the Cleric attempts to use Augury to safely exploit their daily draws from the Deck of Many Things.
Both groups supported by the same rulebooks, but obviously, with patterns of play worlds apart. My Aasimar Ranger/Wizard is just as legal of an AD&D character as someone else's Halfling Thief with six different Psionic Wild Talents, or yet another person's Drow Cavalier.
I think the difference, really, is that modern D&D is far smaller than it was in the past. Oh sure, there's lots of books sold, and lots of people playing, but where once we had vast worlds and possibilities to explore, with so many books, adventures, supplements, boxed sets, Dragon articles, and so on, we have a very small amount of things officially published by the company, and if you want more, you have to make it yourself, or step into the wild frontier of 3rd-party products. Many of which are built on very different assumptions about what the game is and should be- which should be fine, but where once, my table had no issues using a book published by Avalon Hill or the Judge's Guild (several Role Aids books were once seen as essential DM reference guides in memory), nowadays, if you show someone 3rd party book, you might get the stink eye, lol. Hell. You might get that for some official products ("What's this? Some Magic the Gathering tie in book? Get that garbage out of here!").
But I'm just a guy with an opinion on the internet, and I'm sure someone will happily tell me I'm wrong. : )