I've seen a lot of people ask about epic level characters in D&D. I have played a lot of D&D from 1e to 5e with only a short dip into 4e, which was so different (not necessarily bad, just different) that I don't really consider it a "D&D". In every single edition (except 4e which we didn't play long enough), characters reached levels where the respective game masters gave up. They could no longer craft interesting adventures.
Plain combat doesn't seem to be a problem with epic levels, I played computer games back in the early 90s that already got that fine by just limiting the whole gameplay down to combat.
Skill challenges could simply go up. For every epic level rogue there can be crafted an epic level lock.
But with all the utility power that pure casters get, we could not craft adventures that were challenging yet not totally overboard. All the challenges of lower levels suddenly become something you solve with a spell. And while it's still a challenge if only the wizard can fly for a few minutes to maybe get a rope over a chasm, if at higher levels the whole party including henchmen can fly for days on supernatural steeds, the challenge is gone. All walls are passable, all mountains easily circumvented, all mundane enemies easily slain, every weather condition easily changed, every thought and alignment easily scryed, masses of people charmed at no cost.
For our groups that meant that for the DM to craft an interesting adventure that was more than "go get him and whack him", suddenly normal people had immunities and protection we could not have afforded at level 10 and natural anti-magic fields were abundant. It got more ridiculous the farther we went until the DM gave up and called for new, less advanced characters.
I was brought to D&D by the Dragonlance series of books and I do remember the parts where the mage, having attained some sort of epicness, challenges the evil goddess. But apart from challenging a god, what adventures do you play? How do you challenge players with that much utility power?
PS: I do play a lot of other systems and those that have very powerful characters also have very powerful constraints. D&D doesn't seem to have such constraints, there is nothing in the rules keeping you from actually using your powers to it's full extent.