"spammy/toxic instances" - Meta are a toxic company. They literally have blood on their hands.
"too liberal with defederation" - we're talking about one body specifically; Threads. Nothing else.

As to whether it should be done at an admin or individual level, I have no idea. But they're an unethical company and people less privileged than you and I have died while they profit from it. That alone is enough reason for anyone with empathy IMO.