Ah, gotcha -- I'd read your initial post as being about the data being scraped/sold, not deleted/taken out of someone's control.

But even there, unless you only stick to nostr or a few similar tools, there's loss potential everywhere -- I may have some of my SN posts saved, since I often compose them offline, but not all of them. And probably none of my comments. Ditto for a bunch of other sites from Livejournal to Reddit. Most are probably ones I'll never need or want to revisit, but there are probably some exceptions I'll lose at some point.