The lack of deeper integrations between different app types and the federated identity issue (every instance their own signup and user acccount) form significant barrier to widespread collaboration is my general observation.

For instance in any well-received toot with a link to a SocialHub forum topic on average no one takes the effort to respond on SocialHub. Mostly the discussion remains microblogging, and then it sinks into history when activity peters out. The insights and collective knowledge isn’t gathered and lost.