Hardly. It's not like D&D invented the genre, then used Wish to go back in time and inspire REH. It's just easier than typing "high fantasy and swords & sorcery and related sub-genres."
Oh! one of /those/ Niven stories. Got it now. Yeah, D&D does fail to model Niven's 'mana' vision of magic pretty thoroughly (popular old school 'mana point' systems notwithstanding). But it has no problem creating functionally (will let you gank the guy with the magic sword) similar anti-magic shells or Mordenkeinen's Disjunction (a good deal less inconvenient, too). No problem delivering very high-damage astrologically-themed effects, including meteor swarm and comet fall.
Well, first of all, AD&D did do a lot to try to balance classes. It just failed. The attempts, however, were manifold. Wizards, in particular, started out extremely fragile, banned from using mundane armor and all but a few weapons, and with only a single spell (and if it wasn't Sleep, too bad). The idea was that your wizard dying at first level would make up for him being overpowered at 9th level, and campaign-wrecking not long after. I don't think I have to point out the issue with that kind of balance. Casting was also made very difficult - spells took a long time to cast, could be interrupted with attacks, and were both spoiled and memory of them lost if you took even a point of damage or failed a saving throw. On the other side of it, fighters started out durable in basic combat and eventually got pretty awesome saves, and EGG weighted random magic charts heavily in favor of items useable by fighters, so they'd have some more options at higher level.
Every subsequent edition has eased restrictions on casters, and most have not proportionately decreased the number or power of their spells to compensate.
5e wizards, for instance, prepare their spells separately from their slots, and expend the slots to cast them without losing preparation, combining the strategic flexibility of traditional Vancian casters with the tactical flexibility of the 3.5 sorcerer's spontaneous casting. Spells cannot be interrupted, do not provoke OAs, and do not even suffer disadvantage like a ranged attack if they force a save, instead. Casters can prettymuch stand in the middle of melee and blaze away. They have fewer spell slots, but the save DC of all their spells is based on proficiency instead of spell level, so they actually have more spells that have a good chance of working for a baseline build. In addition, they have some spells that can be cast without even consuming slots, and at-will cantrips, as well. So the 'run out of slots' balancing factor, in spite of technically having fewer slots, is actually less of a limitation to them.
5e hasn't left most spells exactly the same, but reigned them in some to compensate for easing up so much on how limited casters are. Some of 'em.
While I don't deny the game's combat focus, DPR machine <> agency. You'd at least want some tactical depth to claim that. At very least.
I don't know where you get either of those impressions. 5e fighter do a lot of damage by making multiple attacks with a weapon using a fighting style they picked at first level. You can, as with any class, tack a couple of proficiencies and a perk on it with a Background - and the fact that's actually kind of a big step forward for fighter as far as its non-combat abilities go is a pretty sad comment on how little has ever been done to address that complaint. That's about it.
I think it's helpful to see the trend. The fighter, in 0E & 1e, really defined the tank role. It's job was to stand in a doorway or 10' wide corridor and hit things and take damage so it would die before more valuable characters. Not the greatest role ever, but useful. As long as you were in a dungeon. Later in 1e and in 2e, it changed what it did best and became a TWFing weapon-specialist (or archer) that just did nothing but dish out broken amounts of damage. Technically it still took up space at the front of the party, but things died so fast it hardly mattered. And of course, like everyone else, it could choose a kit. Not that fighter kits were great or anything.
Unfortunately, that is not a big step forward in any other sense. Did the 3.x fighter build on it. No. It took off in a different direction, backing off a little on damage potential, but becoming a remarkably customizable class. Not too versatile once you'd customized him, but temptingly ideal for all sorts of 'concept' martial builds. It was also completely overshadowed by casters by the time you hit double-digit levels, completely dependent on magic items for relevance, and, often, that wonderful concept build wouldn't 'mature' until 6th or 8th level - a narrow window of 'fun' but better than nothing, which is what the fighter was used to. And, did the 4e fighter build on that progress? No, it was backed up to being an early-1e tank and just made better at it, then given a little tactical agency in the form of AEDU martial maneuvers called 'exploits.'
And, did the 5e fighter build on /any/ of that? Nope, it just retraced it's steps back to 2e, and became all about high damage from multiple attacks, plus a Kit. I mean Background.
Edit: Ok, actually that last bit was unfair. Backgrounds are significantly better than 2e kits. Well, 2e fighter and thief kits, unless I've forgotten something good. And the 5e fighter does have vestiges of the 3.x fighter's versatility in fighting styles and archetypes, and a vestige of the 4e fighter's tank role support in one of those fighting styles and an optional feat. And everyone got HD, of course. And, of course, the Battlemaster got a really microscopic vestige of AEDU - just without the A, D, or U - in the form of 'maneuvers.'
There. That's fair.
