Do you mean that the OP decides which replies under their note are spam?
It sounds like a good way to decentralize the decisions, and to limit abuse of censorship by making it cumbersome to block all of someone’s notes (and even then you can only censor them on your own threads).
There is still the option for someone to abuse it - in a way: if someone that the OP dislikes leaves a reply, or perhaps multiple replies are calling out the OP for scamming, for example, it gives the author of a thread a sort of immunity from criticism (or at least a way to suppress it). And while others could always post *about* the original “malicious” (or w/ev) post, it wouldn’t have the same effect and you’d lose the natural balance of human organization to call out various forms of bad/antisocial behavior. (Of course this cuts both ways — on one end of the spectrum, it’s “canceling” someone, and on the other it’s the power to unilaterally silence one’s critics).
Another potential is that it’s also cumbersome to manage situations with high volumes of spam/scam, in that it would require each user to police the replies under any/all of their own notes and that just seems like a lot of effort. And for the users who don’t bother, then I can imagine scenarios where a thread becomes unusable for anyone who’s actually trying to engage with it.
Still, it’s a thoughtful approach and I can imagine potential for an OP to at least give some indication that there’s spam in the replies. I envision a future where the “web of trust” concept takes these various approaches in concert and applies weight in an intelligent way. Maybe