All those federated platform will only become popular if the backend is dumb and the frontend is smart, i.e. you create your account on a frontend but can use the same credentials to connect via another frontend and no matter which frontend you connect to, all content for the platform is accessible to you, there's no admin having control over your experience, only people offering different UI experiences. Federation/defederation/deciding to host NSFW content, that's all taken care of behind the scene just like on Reddit, for the user they're just using Lemmy via frontend X or Y and they decide what communities and users they want to block.
Everything trickles down here anyway. If you're ONLY on Lemmy and Mastodon, you're still getting way more actual news than the average joe. Popular, shmopular.
I'm trying to remember a time in the last thirty years where something becoming popular made it better. It's usually the opposite.
This practically means nothing tbh. Social networks when they gain economies of scale due to the network effect will effectively shed all the pretense of open source and open platform etc.
We've seen it with Facebook, Google, etc, during the 2010's with closing of chat standards and destruction of XMPP. Reddit 3rd Party API access is another example of this. We'll see it again.