Actually that stuff was still in. ...
I have 10 years of threads that disagree.
Grognards typically had hard base assumptions for the foundation of the game. Class X can only be Race X. Class Y must be Alignment Y. Race Z can only be Class Z. Race Q is banned. Rules AB and C are in use and enforced. But once you play, you are very free.
Your characterization of the games of grognards is almost entirely opposite of my experience of 40 years of D&D - which has spanned a wide section of DMs, from those over 20 years younger than me, to ones 20 years older. There are some DMs that fit your description, but the majority are creative and open.
New Gen typically is more free in foundational control. Races A-M and/classes N-Z are allowed. Restriction 1-19 are removed.
That does align with the description of a lot of younger DMs - the ones I have played with at least. They are bound by the books and have been hesitant to be creative.
However ifyou play a warlock, your patron will bother you and make demands.
...and this is where our experiences differ. This is one of the
key tests I have when talking to a new DM to determine what I want to play in their games. I ask them, "If I played a [XXX] warlock, how much would my patron impact the game?" Then I listen to how they describe the interaction. If they're excited and passionate about it, that is a great game to play a Warlock, Cleric, Paladin, or a PC with strong loyalties to an NPC. These are the DMs that see a warlock as RPG gold and give you a great story in addition to fun combats. These are the games where I dig out the character ideas with a 10 page outline of a backstory that we go over, tweak to fit their game, and then spend 2 years appreciating the narrative that grows from those seeds.
If they show no excitement about it, then I tend to play characters that are mechanically fun, but I don't waste the RPG gold there. I'll build a fun character, and I'll bring personality and drive to the game... but I won't expect the DM to be weaving my character into the story in the same fashion as those excited DMs would.
In my experience, I find more excitement and drive in older DMs than I do in younger DMs. I've met a few young DMs that are trying to emulate Mercer's style, and I always let them know that I highly appreciate what they're trying to do. However, I know a lot more older DMs that are very skilled at this style of game - and most of them are not emulating Mercer - they're practicing the art they've practiced for 30+ years (though I do encourage every DM to spend a little time listening to Critical Role and critically thinking about what Mercer does that works that the DM in question does not do - he is an amazing DM and being able to study his style is a blessing).
Side note: Critical Role has a series called 'Between the Sheets' where the cast give their origin stories and get a little tipsy. Matt Mercer's is interesting for many reasons - and one of those reasons is to hear his story of how he came to D&D and how he thinks about the game and what it can offer. That is highly relevant to this topic. I think every DM out there can get some real benefit from listening to that interview.
However you PC will be weaved into a plot as the games tend to be more narrative. If you pick wizard, you must choose one of the Wizard houses even if you dropped out of Goatboil's School of Magicians. Andthe elves are in civil war, your elf must have an opinion AND it will matter.
This is your brain. This is your brain on drugs. Any questions?
Choo Choo Here Comes the Train! ALL ABOVE THE MAIN PLOT RAILROAD!
If your point was that younger DMs tend to rely more upon the railroad, it is my experience that railroading exists in all generations of players. DMs that are very good at running true sandbox games, like Matt Mercer on Critical Role does, are rare. My own preference is a bookend approach - levels 1 to 4 are generally a railroad that brings the party to the sandbox. Then they play in the sandbox from levels 5 to 16 that lays the foundation as they build up to a railroad finish that ties up all the loose threads to give them that sense of completion when the PCs retire between levels 17 and 20.
Also, I have a series of house rules. The idea of house rules seems to be disparaged quite a bit in this thread. My house rules reintroduce more types of vision into the game (infravision, etc...) They give a benefit to flanking that is less useful than advantage, and strategically reintroduces the idea of lock down maneuvers (without making it overpowered). They give some light mechanics to certain elements of lore from the setting that has existed for 30 years. I have a section describing "THE" textbook on magic and monsters (which essentially has everything in the monster manual, the spells section of the PHB, and the magic item section of the DMG in it).
However, many players in my group never even read those rules and that is perfectly ok as they're all fringe.
However, when they go out into the world, they find monsters that are not in any 5E book, they encounter spells that they've never seen and are excited to learn about, and they never know what to expect. They have to look for context clues to figure out if they're fighting a monstrosity that uses brute force, an aberration with supernatural abilities, or a few creature with trickery and magic. They don't just hear half of the description and say, "Ah, grells. I know how to fight them." I find that players really enjoy the experience of the unknown when it is dynamically introduced. I always evaluate the extent to which it is enjoyed and adjust accordingly in my planning, but adjustments are usually tweaks to avoid approaches that are not as well appreciated (some gamers do not like cute, others do not like scary, others do not like moral ambiguity).
As a player, I always ask a DM about the games they run before I play with them because none of these generalizations are universally true, and each person needs to be evaluated for who they are, not the generation from which they come. I encourage all players to do the same - get to know the DM rather than having a preconceived notion of who they are based upon their age.
are actually better than all of the above.
