The flight from Musk's Twitter to the "free" fediverse never really took off.
Aside from the usability learning curve he talks about, the other very pointed criticism is scalability problems that instance owners face. From what I understand, Lemmy and Mastodon are both similar in that they use the ActivityPub protocol. Could Lemmy get too big to scale and still be decentralized?
To piggyback on that Linux analogy: if ActivityPub becomes as essential of a backbone to the internet as we know it as Linux servers are then the transformation has happened IMO.
There's a key difference. ActivityPub is a user-facing technology, in terms of the way data is exchanged.
Linux as the backbone of the internet is not user-facing.
The average user doesn't care or even know if some web server is using Linux or not. The average user does care if it's difficult for them to find and see interesting content on their content consumption platform.
We need to improve the new user experience and ways to introduce users to content they may care about. We need a way for instances to have awareness each other and what communities are available without user-initiated federation. Maybe we need some semi-federation by default. Or maybe we need some global index that all instances can share. Ideally, we should have some kind of recommendation system at the community level to help users find communities they may be interested in.