A free Discord with 4,000 people looks busy. It isn't. The people who would actually help you are gone by week two.

The fix is simple and unpopular: charge, keep it small, and make every post cost something — time, a real question, a piece of work. If someone won't pay $29 to be in the room, they weren't going to contribute anyway.

That's the standard here. If you ship software and want a room that isn't a timeline, the door is open.