It’s the same vicious circle. People login, check out what’s happened since last time but don’t actually post anything (or vote or comment etc) then leave. The next person does the same, also sees that nothing has happened and also leaves without interacting.
Obviously, I post stuff every single day, often several things, but it’s SO hard to get other people to interact. This month looks like it’s going to beat last month by around 20-25% on total visitors, but that doesn’t really count for much if no-one posts anything.