Or mods could just apply rule #1 more often.
True, but that's a massive workload. It would need several dedicated mods just for that board.
There is enough space in the Off Topic board for all sorts of garbage, bitcoin-relevant or not. It's not like having a Flat Earth thread next door is preventing me from discussing some nerdy stuff, it's the shitposting hordes that make it insufferable.
A topic about which browser is best for privacy (for example), whilst not really belonging to Beginner's and Help, at least gets some decent discussion going and gets seen by a good number of more senior members. Post something like that in Off Topic and you would get 5 pages of nonsense saying Chrome is best before you got one meaningful response. I'm not saying you can't post meaningful stuff in Off Topic, just that as it stands, there's no point if you actually want a proper discussion.
I think the bigger problem is that if Off Topic (or any of the shitboards) gets moderated then shit will migrate elsewhere.
Yup. In the past few weeks I've been paying particular attention to the Press Board. I've had over 50 topics trashed from there in the last month, and a handful more locked, which is significant considering it usually only gets 2 or 3 new topics a day. The usual suspects quickly spilled over in to Bitcoin Discussion, Trading, and a couple of other places instead. I wouldn't want to get rid of or overly moderate Off Topic for that reason; spammers gonna spam, so might as well try to contain them somewhere. But it would be nice to have a non spam filled board for "other topics which are of interest to bitcoiners".