Do you expect that nerfing casters would be fun for caster players, or are you only concerned about martial players' fun?
I think it depends on how you approach it, as Ive communicated multiple times in this topic, to the point of laying out explicit examples of me designing mages precisely to my given specification. I have Mages that can literally rain down magical nuclear bombs every single turn and its actually
slightly weaker than an equivalent AOE martial, and all 4 class types in my game are equally capable at the utility game, even with protected niches included.
Magic is
easy to make fun, cool, and exhilarating, and you
do not need to make them mechanically busted to do it. (A statement I have also repeated more than once)
Trying to design the "Universal Fighter, but Mythic" is just retrodding the same path the 5e Fighter did. You're not going to be able to design a Universal class thats going to be appealing to all of the people that its meant to appeal to and also specific enough that it actually delivers on what its supposed to deliver.
What genre is a universe spanning, psychically connected array of super-intelligent brains that traveled back in time to save their reality spanning empire from collapse and are taking over reality once again? Is is the same genre where you could easily find a dragon ascending to godhood by connecting its soul to all versions of itself across a multiverse of time and place and read the echoes of time? Maybe it is the same genre where you help the child of a god find his lost cat so he can sleep at night.
DnD covers all of those, so which genre is that? Is it sword and sorcery with its gritty blood in the sand? Nope. Seems like it is something different.
Thats funny, because thats exactly what we're telling you is the problem and why parts of the game aren't cutting it.
At what point does the game no longer work? 5e is hardly perfect, but it works, for most people, right now. Or do you just mean the game doesn't work for you?
I do appreciate how we're circling back to the same arguments over and over, like this isn't the umpteenth time you or someone else have made a nonsensical accusation like that just to try and eek a win in an argument.
Im on the side that doesn't think the problem is very severe, remember? Trying to accuse me of thinking 5e doesn't work when theres countless pages of me arguing otherwise is just, wow.
And as for when the game stops working, Ive yet again
repetitively pointed out that all-caster parties are
extremely difficult to DM for and that
doubling down on that happening all of the time is
not going to result in a better experience for anybody, least of all DMs that already get the short stick as is.