People who don't fully understand certain emerging technologies are free to spread FUD about that technology to their hearts content.

Nevermind that the Fediverse is not an emerging technology, having been in operation for almost 13 years* at this point.

* https://web.archive.org/web/20201028234912if_/https://mastod...

* https://web.archive.org/web/20210124192004/https://social.di...

That analogy is a bit too harsh. How about like saying you went to Texas but then only visited Austin?

No, it's not too harsh. A Mastodon instance doesn't even give you access to Diaspora* users.

Diaspora is not part of the fediverse and never has been. Diaspora is federated but has always used their own, separate protocol.

There are three main sections of the Fediverse: OStatus, Diaspora* and ActivityPub. Most OStatus systems have migrated to ActivityPub, but Diaspora*'s still separate. https://friendi.ca gives you access to all three.