I'd argue all Q&A services devolve into madness when they get mainstream.

Before Quora we had yahoo answer and before that surely something else.

As soon as they get mainstream the quality of question and answer goes down. Those systems only work with well defined constraints either on the subject of the question or the validation of the expertise of the people answering.

All of those platform just open the valve with close to no moderation. We can see the same with Reddit and big sub Reddit.