Right, which is why my article has this paragraph:

>I say “Mastodon” here because if I say “ActivityPub” instead, a crowd of people will show up and say that actually what I’m describing is how Mastodon chose to implement ActivityPub. Whereas ActivityPub by itself does not really specify how to actually use it in practice.

I understand there's other ways to use AP, but when people say "where are Bluesky instances" they are specifically comparing AT to Mastodon's AP topology.