If "some jerk" deletes my post, it wastes my time, and will cause me to reply less in the future (to everyone else too), that's the "chilling effect" I was thinking about.
Ultimately, I think the poster/replier should own their own notes (undeletable), that's like a basic principle of nostr.
I tend to agree with
@DanConwayDev that reports (kind 1984) seem to be the best way to do this. I can reply to you, and you can tag my reply as low value/spam, and other readers (or their clients) can decide for themselves.