We get quite a few questions every day from users who somehow get lost and ask questions that are completely off-topic here, mainly users who seem to think they are on Stack Overflow.
I have been thinking about this a bit lately, and think I might have some sort of a solution: what if users needed to have maybe 10 reputation on another Stack Exchange site to participate in Main Meta?
I think this seems like a good solution. It would make it impossible for lost users to have their first posts be here. From what I've seen, the vast majority of users who post blatantly off-topic questions have no other accounts or no reputation on their other accounts.