I’d like to throw in my hypothesis that build variety is influenced by game difficulty. If the game is “easy” and you can clear high end content with many builds, it will increase build variety. Naturally if there is only a handful of builds that can clear T4 dungeons, players will tend to play those builds.
That is why I am a bit dissatisfied, because T4 dungeons are more difficult than endless content like MoF or arena. I think it should be the other way around.
That said, there will always be players that will play meta builds and always be players that will play non meta builds (insert @Heavy) no matter what.
Epoch Builds / Dread once said that you need 200k dps for good endgame clear speed. This is not so much. So I agree with the sentiment that defenses are more essential.