I think you're spot on with account thing. When I first came to the fediverse, I thought the distributed system was cool, but then I saw the interoperability between different software and though ok, but why would I want to?

If someone posts a peertube video within the medium of lemmy, I also want to discuss it within the medium of lemmy, after all, there's a reason they posted it here. I want to do it in this community, using this identity. If I wanted to comment on peertube, I would go to peertube.

So the only benefit I saw was that you could use one account for all my social media, as convenience. But of course, that's not how it works. The interoperability is just a half baked sending messages thing. Because they are fundamentally different platforms not carefully designed to work perfectly with every other platform in the fediverse. There's no central account, you sign up for a specific software, on someone's instance.