Try to grow lean.
What mistake that quora is making is that I don't think it is growing lean. They don't even seem to know that their users don't like few features and their some features that can be good and are required as hell sucks.
This can be taken advantage of. Try to grow it lean, constantly check if what users really wants. Quora seems to have got diverted from product based philosophy to revenue based philosophy, this should be completely avoided.
Be close to users, get "real feedback" and work on it, endlessly.