@Gargron I sympathize with the argument I've seen that it feels like the added portion to the quoted post adds very little, usually. But I think that it's no less trivial than any given random user's sparsely viewed posts anyway, and alas, I and clearly many others are still trying to find a way to share posts and our replies to them in an intuitive way.

One way I've seen is someone replying to a post and boosting their reply. On birdsite, replies and QTs were super separate threads, but maybe on Mastodon they could be implemented as a type of reply that simultaneously boosts (at least from a UI design perspective) both posts together? What I mean is a reply that shows in my followers feeds and displays the replied-to post above it, thread style. Perhaps this could also help with the issue of implementing permissions controlled by the original poster.