At the moment when a new user gets downvoted, he or she has no idea what's going on, and while I do think that spending at least a minute to go through Tour is a good etiquette, most people just don't do it. The purpose is to keep SO of high quality and it would be so much more helpful if new users actually understood at least some of the rules, rather than simply getting new accounts or leaving in frustration.

My suggestion is to add automated standardized comment when a question from a new user gets, say, three downvotes. It can link to Tour / FAQ and say something along the lines of "Your question has got a few downvotes. It indicates that the community doesn't find your question useful and / or it lacks research effort. Please take a Tour to learn how the site works." The author can be Community.

I feel like it will benefit SO, as new users will have a better idea about the workings of the site. There is not much benefit in downvoting user to -10 if he or she doesn't understand what's wrong.