Eh, not like it changes anything on base concept.The obvious solution is what they ALMOST did with Dynamax, making it so that legendaries can't use the generational mechanic. If that was an actual universal rule, it'd help keep the busted regular mons on-par with the BST 680s. Yes, that screws Zapdos etc, but it's at least better than DMax Kyogre.
A similar example is the pre-home Ubers, where they had that "dynamax clause lite" where you couldn't dynamax the restricteds.
It's not like it changed anything ultimately: it'd still be a select few that would abuse Dmax.
In general, it's a similar "problem" to when I contest people who say that metas without legendaries would arbitrarly be better: no, you just change who the top 10 are. Expecially as in the case of the gen 8 leges, while they couldn't Dynamax, all of them were inflated in stats & given tools to nuke Dynamax.
If you prevent a group from using <insert mechanic>, all you do is make the next best use it instead.
Mega Evolutions were a clear example too: despite a significant enough amount of pokemon having access to it, in a given tier you'd really only see 2 or 3 of them if even. Mega Blaziken was in ubers but noone used it, why use it when you can use Mega Salamence or Mega Gengar?
You could tecnically use Mega Beedrill in OU, but why bother when you could use Mega Mawile, Medicham or Charizard?
Ultimately, no matter how you slice it, any mechanic will always end up being used by "the top X" that can use it, with all the others capable being ignored.
At that point, "generic mechanic" at least still gives you the option to use it on the fringe cases in some situations. I think it's better conceptually than "target limited" ones.