IME chat attracts people who devote a lot of energy to the topic, including top contributors and power users. If you have questions about the latest features or obscure use cases there isn’t a better place to go.
Forum and wiki are great formats too, with different strengths. But if you are frustrated because you can’t seem to find help in those formats, head for the chat.
Some communities archive their chat. This seems like a great source of data to bootstrap a wiki or faq.