To be fair, with all those Master Hands, I think we're getting more than just one snap.

I'm sure that Thanos could destroy the entire universe if he wanted to, it's just that those weren't his goals/intentions. All he wanted to do was wipe out half of the life in the universe for the sake of balance, not for the sake of utter destruction.

Seems the intentions of this new baddy were specifically to wipe out everyone to then harness their spirits to put into the copied/cloned bodies of the fighters.