I would almost never join a Discord/Slack to ask some specific question; I always ask people I already know. The level of effort is pretty high! Join, learn rules, figure out where and how to ask a question, then sit there and monitor things synchronously so people don't ignore you/forget you.

I really, really miss the abundance of forums. The only thing like them left these days with any sort of population is subreddits. There are still forums dedicated to niche topics, but they're rare.