I'm interested in Pixelfed, but I have to admit I don't really understand it. Specifically, why does it need to be a whole separate service as opposed to, say, a Madoston client that specializes in photo sharing? Or just a separate section of an existing Mastodon client that specializes in photo sharing (like a 'stories' kind of thing)? I feel intimadated by the idea of essentially joining a Mastodon-but-its-only-photos and rebuilding a whole new social graph just for that. What am I missing?