Diaspora used to be great! The problem is that, as a project, it's been kind of rudderless in direction for a long time. It's been in maintenance mode for nearly a decade, where contributions are largely just random fixes and minor improvements sent in by volunteers.

Unfortunately, the old guard is very against adopting ActivityPub in any way, shape, or form. Historically, the project has always kind of put the expectation of federation compatibility on other platforms, rather than doing any work to collaborate with existing platforms or adopt existing standards. They can't even communicate with most of the Fediverse these days.

The project's future is kind of uncertain. They finally got a developer API put together, and work is happening on Account Migration. But, the platform is slowed down by years of cruft and technical debt.