Well...that's sort of my point.
We went from
locate city bombs and
the Wish and the Word to...dealing 40% more damage than expected, or having an attack you could potentially juice up so it could kill a god in one blow if the stars aligned.
That's ENORMOUS progress in terms of getting busted-ness under control. Being "busted" is both a matter of degree and a matter of kind. Your statement pretty much implies "never, ever bother trying to balance. You'll never make ANY progress, whatsoever, no matter what you do." And that's objectively untrue. A single example of a broken power certainly does not indicate that high-level gameplay is always busted, still less that it is always horrifically busted rather than just a little wonky.
You'll also note that I did not say--and certainly did not mean to imply--"that high level play is never busted." I was, in fact, specifically trying to
avoid saying that. Because I absolutely agree that you usually can finesse and finagle and push and prod and tweak and shift, and
enough of those stacked together can lead to weirdness in much the same way that a stack of identical books can remain balanced despite having books
arbitrarily far from the table...if the stack gets tall enough.*
What I am saying is:
(A) We can do better than we have in the past. We can learn from past mistakes, and improve.
(B) Different kinds of "bustedness" exist, not just different degrees, and fixing the worst kinds is worthwhile even if the lesser kinds remain.
*Each book is balanced so long as the center of mass of the stack remains above the table. The maximum distance you can push things for N books of unit length is half of the sum of the first N harmonic numbers, (0.5)(1+1/2+1/3+...+1/N) This is a divergent series, so you can get distances arbitrarily long. However, it converges with a logarithmic growth rate, meaning you need only 4 books (because half of the sum of the first 4 harmonic numbers is 1.041666...)
(This is kind of cynical; usually I give WotC a fair shake, because I believe these decisions are really made by suits who don't care about D&D players, they just want money. But it really doesn't matter- whether you have integrity as game designers or you're held hostage and forced to churn out easily digestible junk food that's slowly killing the people that eat it, the end result is the same. So here I am, live and uncut. People are going to either disagree or agree, I don't think anyone is actually going to change their opinion now. But here's my rant anyways, because I can't just say nothing, even though I am but a voice crying out in the wilderness...or an old man yelling at clouds).
No, it's not that you can't achieve balance. But not only are there issues with achieving balance because (forgive me for using italics, but I need to stress this)
not enough people can agree on what balance is, nor are enough people interested in balance in the first place- either because they don't see any imbalance in their personal games, they think they have it covered, or, the position I understand the least (but tried to at least explain),
they believe that the game is better without it.
Specifically with regards to high level play, it will remain busted until the company that makes the game cares enough to balance it. They don't. That's obvious. There's not enough money in it.
They are building the game for some "sweet spot" that they feel most games are run in. They want you to quickly fly past the first couple levels, which they feel are the least fun and hard to balance, since they are incredibly swingy- but are kept around because enough people insist that is when the game is the most fun; I remember how this went in the playtest, where it was felt that what 4e called level 1 was a great place to start campaigns, and WotC initially was going to keep it that way, but a lot of people called for the game to "start" at an earlier point, with less resources...for reasons.
Reasons I don't get. I don't run games at level 1, and I haven't since 1994, simply because I got tired of people making characters, then having those characters die any actual threats, from a random goblin throwing a spear, to kobolds, to effing tasloi (there's this fluffy low level adventure in Dungeon where some tasloi are keeping a faerie dragon hostage because they are...problematic now, I'll grant...addicted to it's breath weapon. I thought it was cute. It was a bloodbath).
3e proved to only be marginally better at handling level 1, and when 4e was like "hey, why don't we start with 20-30 hit points" I was like "THANK YOU".
But some people are really attached to the "zero to hero" loop, and want death to lurk around every corner and for players to feel cautious and meek- and you know what, that's fine, I don't think it's very much fun to run or play at those levels, but if it works for them, I can start at higher level, that's fine...except...
At a certain point, WotC stops really caring. Past level 10 is this vaguely defined zone of super powers and too many resources and enough of a hit point buffer that any reasonably decent group is going to cakewalk all but the most unfair encounters. Casters gain tons of "I win buttons", non-casters gain very meager abilities; in the case of the Fighter, just more of what they had before.
The CR system falls apart because it's based on largely nothing, monsters were never designed going "but what if they have 90% resources? 60%? 20%?" because they likely assumed that any group that gets too weak will stop adventuring for the day. They never say "what if the group has a Paladin instead of a Fighter? Or two Clerics? Or no Clerics?". They claim "oh no, it doesn't matter what classes you play"...so someone might get the idea that all classes are balanced against one another.
Haha, sorry suckers, that's code for "we didn't even take any of that into account". Your team has four Wizards, sufficient to blow past Legendary Resistance in one turn? Eh, maybe the next fight will challenge them more. Who knows? If they die, well, you can say it was supposed to be hard. If they win, well, you can say "but each subsequent battle will be harder because they have less spells, see?!".
When Crawford is talking about Epic Boons and capstones in the playtest, I'm like, dude, you're polishing the brass on the Titanic, the ship is going down, man! You don't give a damn about high level play! Your "marketing research" shows that most games are over by like, level 7!
Which is obnoxious when you realize that the game is really only balanced for like 4-5 levels, and all the rest of it, your "bounded accuracy" which is meaningless with options in the PLAYERS HANDBOOK, and never takes into account group composition (because you don't care about actual to hit and AC, you only care about HIT POINTS, you lazy bums!), you are fine with Four Elements Monks coexisting with Twilight Clerics because, well, tables will police themselves right? It works for MtG Commander!
I've watched the same decisions get made with regards to high level play for decades. To go on with the MtG analogy, D&D is a turn 7 format and they're fine with that.
All of this New and Improved Flavor 5e? Window dressing, man. So far, they haven't really addressed any actual concerns; it's another 3.5. Some updates, some things people will point to and say "see? This makes the game better!", some nerfs, some buffs, but the end result won't really be any different. They just want to sell you another three core rulebooks at 50 bucks a pop (ha, what am I saying, they'll probably up the price count).
Games Workshop has been treating their fans this way for decades, seems to work for them, and even if you jump off the train, they still got the most popular seating around.