It’s really unfortunate that Lemmy handles deleted posts in this way. It’s one of very few genuine advantages of the Reddit platform. Over there, if the OP deleted the post, the text they wrote would no longer be visible, but all the comments under it still would be. And people could continue to have that discussion, so long as they had the link.
Not even just digital content. This is only half a step removed from right to repair campaigns, and that’s all about physical hardware, ranging from mobile phones to tractors on farms.