Flavor of the month design is terrible.
That said, for some of these builds to become decently viable, they might still need a 90%+ nerf. There are just a lot of builds that need those nerfs.
Nerfing into the ground is not a problem. The problem is that Blizzard then buffs other builds to be broken again, that is what makes it flavor of the month design, rather than just balancing. Intentionally making the game unbalanced, again and again.