On SO, if I include the words "best practice" in the title of a question, I get a message before I even submit the question warning me that the question appears subjective and may be closed.
Could we do something similar here for questions which contain no code? This certainly wouldn't cover all off-topic questions, but there's a fair few like this, which might be filtered out.
The main problem I can see with this is that either the message has to be there the whole time (which might be annoying when you've just started writing a question) or it would only be displayed on moving focus away from the question box. Often I imagine that would be at the moment of clicking the "Post" button which would be too late.
Given how unlikely (impossible?) it is for a question with no code to be valid, potentially we could do something more obtrusive like block submission or showing a modal warning when the "Post" button is clicked.