Some examples would be useful, but I must say I don't really share your concern on this. I don't see many off-topic questions answered here.
At the same time, I do see quite some questions marked off-topic incorrectly. There seems to be a tendency to close-vote on trigger words, while the issue in the question has nothing to do with version-specific bugs for example.
Furthermore, I consider an unjust close vote as a bigger sin than incidentally answering a question that could be marked off-topic. In the first case, you send someone away who could (and should) get an answer here, in the latter case, someone gets an answer in the wrong place.
I don't see your issue that it invites people to post the wrong type of questions here at all. When people post questions that don't belong here, it is because they are not familiar with the SE sites, not because they looked through this sites variety of questions.
On the contrary I would say, in general these people are not familiar with the site at all.