This suggestion is probably the most frequent subject of META threads on this subreddit. While we very much understand why people would like this, there are a number of practical and conceptual issues to do with Reddit's site architecture and the way we actually moderate that stand in the way of it being implemented. You can find a full, recent overview of these issues here.

If finding answers is your main problem, we have several tools and features that can help. Using our Browser Extension corrects the number of comments shown to more accurately reflect what is visible in the thread, while our Twitter, Facebook, and Sunday Digest feature dozens of answers (or more) each week.