It kind of makes me think of how odd it would have been if many of the old forums named themselves like bookclub.phpbulletin.com, metalheads.vbulletin.net, or something.
There’s nothing wrong with doing that, obviously, but it’s struck me as another interesting quirk of fediverse instances/sites. Generally as soon as you visit them you can tell by the site interface or an icon somewhere what software they’re using.
I kind of see where you’re coming from, and I think the reason I wasn’t thinking of it in those terms is that I see ActivityPub as the more important underlying tech across the fediverse than say Lemmy/Mastodon/Friendica/etc.
I say that in part as I’ve come into the fediverse from Mastodon, where there’s more than two options in play, e.g. Akkoma/Firefish/Misskey/Pleroma/etc. each of which has some commonalities, but also some pretty distinctive features, particularly from the Misskey side. Hell, Mastodon itself even has Glitchsoc, which is what the original instance I joined on that side of things runs.
On reflection, I don’t know that the microblogging instances mix in the name of the software they’re using as much, which you’d think with more options they might be inclined to, but the more I think of it the more I remember a lot of them use some fun, odd names instead.
Activitypub is the protocol. Mastadon/Lemmy is the API. Just because two applications share a protocol doesn’t mean they can talk to eachother.
The Spotify app uses the HTTP protocol, like your browser does, but that doesn’t mean you can view any webpage from the Spotify app. Idk if activitypub is actually a protocol, but it is at least analogous.
While it makes sense for apps/networks of a similar type to interoperate (like microblogging), apps/networks of different types may not make sense to integrate.
So for servers on the same network/app, it makes sense to include it in the server name, so that people know what app/network it belongs to.