Often (or mostly) we all encounter, when a new user asks a question that there is no
MWE (done that myself). Also, we mostly ask them to post an
MWE via comment.
So, apart from giving a tour of the site when they join, will it be a good idea to inform the users (only when they ask their first or first-few questions) about the
MWE? For instance, a
marque or a
highlight on top of the page where the question is being typed.