>"And it would make sense to "keep" the replies on a post even when the post is deleted right?"
>"If I had to build this, I would go for the inReplyTo-ish field, and delete the entire tree if the original poster removes the message"
I absolutely disagree with allowing someone to delete the posts of others. If you delete the entire tree when someone deletes their original post, or a portion of the tree for someone who is within the thread, that allows someone else to delete my posts. That's not right. When someone deletes a post I think there should be a placeholder there to indicate that a post was deleted (and who deleted it) so that other comments following that post can be better understood in context.
By the way, I often will link back to threads that happened months or years ago rather than repeating myself over and over again when the same subject comes up again.
Here on qoto, users are allowed to delete their toots, but everyone else's toots are still visible.
Also, this feature that allows users to delete posts that have replies and thus fuck up the thread is exactly why I often quote from the toot that I'm replying to, so my abandoned toot will still make sense -- like I did here in this thread.