The context for conversation is the mai post itself, that's up to the author (and its interest) to keep it published or not. SN already offer the delete option - that great too, but tedious to use each time.
What you say, make sense, and in this way SN will have less indexable contents too. However, it's not really a discussion as it's written and it will stay till someone decide it will.
My point is that SN it's a conversational platform. You here NOW, you get the contents.. if you arrive late, conversation it's gone because the content are blown away by the wind, they stey only on the reader memory. Its a great feature none other platform offers it, nor nostr does.
deleteoption - that great too, but tedious to use each time.+you keep SN db at a minimum size