I would simply say that 5E is better balanced than previous versions (not including 4E because it had a different foundation).
Y'know, "
...except 4e" should just be understood in every
blanket statement about D&D...
5e's slow pace of release puts it at a stage in the inevitable progression of bloat & power creep that's a lot
less problematic than any other edition faced in the fourth year of its run...
It does also have a couple of features that help with balance. Proficiency, for instance, gives an
even bonus progression across all classes as you level, that other editions didn't have...
Sometimes I think we've been playing different games. I've always modified and tweaked the game to suit my needs and to fit the group in every edition.
Modifying and tweaking D&D has a long tradition,
D&D has always benefited from being fixed up with variants, mods, house rules, whatever you want to call 'em...
Even when the community wasn't too accepting of house rules, as under the 3.x/PF RAW uber alles zietgiest, if you could pull it off, the game could benefit. (And there were some variants, like E6 that did work so much better as to attain some measure of popularity.)
I've played or DMed a couple of campaigns to 20th now. There were rough spots and a lot of monsters were tweaked using the rules in the DMG but the game was still playable. I can't say that about previous editions.
No edition of D&D has really been playable at high level... And 'high' has often started at 9th. They might have been wildly imbalanced or problematic or lacking materials, but it's always been something some DMs are capable of dealing with - just not so many or so well that high-level games ever saw as much play as lower-level ones.
And, it's not just high level, either:
D&D has always had a sweet spot... A range of levels that it just works better in terms of playability, class balance, encounter balance, setting considerations, etc. It's varied with the edition, early D&D it started maybe as early as 3rd, ended by 9th. 3e, at the time, I'd say managed 1-10, though I was mainly playing in one group at the time, and we eschewed Polymorph and a few other shenanigans that could make things iffy as early as 7th - in a way, the ideal sweetspot of 3e wasn't a level range, so much as a variant: E6. In 5e, I think, there was an awareness of the sweetspot in the design phase, and it's reflected in the exp table. If you compare the experience it takes to get to the next level to the exp budget of an adventuring 'day,' you get an interesting ratio - 1:1, at 1st & 2nd level. It goes up after that, more than doubling by 4th level, stays stable through to 11th, then it gets faster again, about 1.5 days' worth of experience to level from then on. 5e speeds up advancement through the first couple of levels to get you into the sweet spot, then slows down to savor it, before speeding up again after you leave it.
Without that dynamic 5e wouldn't have felt like D&D, so they didn't try to 'fix' it, but they also made an effort to focus the experience(npi) of play in a campaign on that sweet spot. Kinda brilliant, really.
The thought that 3.5 or older editions were better at supporting high level play is simply laughable.
3.5 at least made an effort with the Epic Level handbook, and BECMI with, well, the M & the I, guess it was - I mean, support for actually /being/ a god, right?
I will agree that some previous versions had more complexity. I disagree that more complexity is necessarily better.
Complexity is a price you pay to get something that'll hopefully, net, make the game better. D&D had a lot of needless complexity, back in the day.
But yes. Obviously D&D it's failing by being one of the most successful versions ever released. Sad.
And, last blanket statement:
D&D has always sold better... than every other RPG!
;P