What's stopping these fucks from making almost all final evolutions viable?

All you need to do is change a few stats, distribute better abilities or give better movepools to some pokemon and by doing it, they would fix a major problems people have with the competitive aspect of the game.
It's a much better option when it comes to fixing pokemon when compared to mega evolutions of alolan forms, since both of those require new designs people might not like, makes the original pokemon irrelevant and sometimes are equally as worthless in terms of viability as the original.

So what's stopping them?