There are a couple issues I can see with hosting a semi-regular competition:
The forums do not have a method allowing users to vote. There are plugins that do this, but we'd have to investigate them, work it into the theme, and make sure it cannot be (reasonably) rigged.
While I cannot speak for the others, my spare time right now is very limited, so I would only be able to be of minimal help. I'm hoping my schedule will lighten up a bit in the new year. (I'm hoping that once things lighten up a bit, I can fix the forum plugin and look into the QnA issue :# )
Another factor to consider is that there is a monthly game jam, Godot Wild Jam, that has been steadily going for several months now. Perhaps users participating in the Godot Wild Jam (and/or other game jams) can post here on the forums with their projects?
However, all of that said, if you want to encourage others to participate in a game jam/contest here on the forums, I have nothing against it. Right now, I am personally not in a position to help make/run an official game jam/contest here on the forums, but there is nothing stopping anyone from making a Godot forums game jam if they want. :smile:
(Disclaimer: These are just my personal thoughts on the matter)