The goals of federated social media and corporate social media. Unlike siloed corporate social media, the fediverse platforms are not meant to compete with one another for being the 'top dog' so to speak. The idea is just diversity amongst the platforms and different options for people with different preferences. Since the fediverse is not concerned with revenue or appealing to a venture capitalist, competition is unimportant and I hope it stays that way.
In a way they do. At least the instances don't compete, but the users do. Example, there could be a meme community on two instances. Users will probably gravitate towards one. The downside is that smaller communities get buried. Most of the smaller communities I'm subbed to on Lemmy don't ever pop up in my hot/active. Reddit was a bit better I think and smaller/less active communities popped up in my front page more often and felt more balanced. I think the hot algo in Lemmy could be tweaked to be more balanced like that, would also help the competition.