The issue in my eyes is that things like Mastodon are pretty well designed for what it is. A main feature of ours is the personalization and separation which we could have hacked into such a protocol but ends up being a worse experience for the majority of the users. Personally I wouldn't want to use a fragmented network to connect with people I know in person (Friends, family, co-workers), but I have no issue with it for online communities. In the end though, I think fragmentation doesn't help simplicity and simplicity is what the majority general social network user is looking for.