[the_third_wave]

If federation works as intended this should not be a problem since it should (...) not matter whether someone uses server_X.org or server_Y.net. As to whether this works in practice I have no real idea. I have self-hosted a number of Peertube instances which also support activitypub and am on-and-off experimenting with a Pixelfed instance ("Instagram goes activitypub") but since these are all small-scale experiments they neither prove nor dispell the utility of activitypub-as-a-protocol.