Compared to a site like Quora (where I'm a Top Writer), musing.io has a lot less depth of interesting questions and answers. It's less good at identifying answers that are interesting for me to read.

While I could point to some features of Quora that musing.io lacks (like the ability to use LaTeX in math answers!) I don't think those are serious drawbacks. The biggest obstacle is probably that you have to be on the Steem blockchain already in order to contribute questions or answers--- and the signup period for a free Steemit account is still quite long. It was about four days when I signed up, and there's no way I would wait four days merely to ask or answer a question on musing.io. This will probably continue to be a drag on growth.

A Q&A site needs to find a way to bootstrap an interested and interesting base of users, which is not an easy problem. musing.io offers just very small payments even to very committed users, and poses a severe obstacle to casual users.