I disagree with lemmy.world’s decision, for three reasons:
Address problems as they appear - negligence is bad, but so is jumping at the gun.
Locking users out because they’re misbehaving is different than locking them out under the assumption that they’ll misbehave.
Given that lemmy.world is a generic purpose instance, odds are that it would work better by letting users sort themselves out, and only intervene on problems when it is not reasonable to expect users to do so.
I also think that lemmy.world’s current size in comparison with other instances is a bit problematic. It’s great to see instances growing but it would be better if said growth was spread out.
Just my two cents, mind you. I’m from neither instance.