There are still many questions in SO being asked that are tagged [latex]. Should we advertise this site over there? In a comment perhaps? what is the official take on this?
I would suggest that those of us who are active on SO should keep an eye on the
tex tags and simply suggest, via comments, that they try their question here. Nothing heavy, just a suggestion.
If someone spots a question there that makes them think, "I'd really like to know the answer to that." then I see no harm in reposting it over here (with due attribution) and putting a link in a comment to the question on SO. But I'd recommend only doing it for questions that you feel you are able to make your own question (so that, for example, you would feel no hesitation about accepting a particular answer).