I really couldn’t care less if I can follow a Lemmy community with my Mastodon account or comment on a PeerTube video with my Lemmy account.
Don’t get me wrong, it’s neat and a cool achievement of the ActivityPub protocol, but that’s like advertising that your awesome new solar-powered, self-driving, flying car also has power windows. I’m glad it’s there, but there are way better things to talk about, especially when trying to convince a newcomer to jump on board.
At the end of the day these platforms do one thing, deliver content. Ideally with proper federation you’d never have to screenshot a post from one platform to repost it 100 times to another.
Also, like it or not, for every bad idea on platform X, there are just as many on platform Y. The biggest differences come down to how the content is sorted, presented, and interacted with.