1) Entertainment of yourself and others.
2) Promotion of yourself, others, or certain ideas.
3) Assistance of others (which is theoretically the purpose)
4) Experimentation and refinement of your arguments.
(1) is obvious but isn’t very valuable to anyone.
(2) is probably a misuse (free riding) and tedious.
(3) is the target idea but the question is what percentage of answers meet this criteria (not many).
(4) is the scientific approach to debate structures.
Personally, how I benefit from Quora is that it provides a large body of questions that are asked by people who are curious, and arguments by a large numbrer of people with erroneous knowledge, and as such, it’s a great place to learn how to talk or write about a subject if you don’t really understand how ‘ordinary people’ think of a topic. The fact that answers are often bad, is actually useful because it provides insight into why people arrive at poor conclusions. Because it is one thing to state a solution, and another to provide a route to it, that corrects the erroneous assumptions of others.