I think a rule-change to prohibit follow-up questions until at least one good answer has been posted would help increase the quality of the subreddit. Too often there are three or four "follow-up" questions on a post that has no answer in the first place. This detracts and distracts from the OP. Let me know your thoughts please.
I completely disagree. As /u/shadowbreakr stated follow up questions can be used to a poorly worded question or an overly broad question. It can also help bring in answers that only partially answer the original question that would not have otherwise been posted in the thread. Since you asked for examples here is one from the front page of today:
https://www.reddit.com/r/AskHistorians/comments/6h7rtv/in_many_medieval_strategy_games_the_army_is/
/u/sunagainstgold was the first person to post an answer but posted it to the follow up question. This at lead to short discussion in the thread that most likely would not have been there had the follow question not been allowed (thus hopefully keeping the "why are there no comment comments out of the thread). Even though the answer does not directly answer the original question, it does provide a little information that relates back to it, and is hopefully helpful to the OP.
And honestly the mods already remove enough posts as is, making them police this also is a little much IMO.
As long as the follow up is related the the OP I disagree. Sometimes the original question is worded poorly or is to obscure and a more general follow up can allow someone to answer that question in depth and in the process maybe answering a small part of the original question.