It basically invites the site's usuals to welcome new users by following a series of patterns that include leaving messages to encourage participation:
Here's the pattern I usually follow:
I wait until I see a question or answer from a new user that I think is on-topic and at all valuable. (If I'm not sure if the user is new, I click into the user profile and see if there are any prior valuable questions or answers.)
If the content is upvote-worthy, I upvote the question or answer.
I leave a comment on it starting with something like:
@user, Welcome to Mi Yodeya, and thanks very much for the [positive adjective] question/answer! If the question or answer could use some improvement (e.g. adding a source), I add guidance to that effect.
If the new user is unregistered (which will apparent from the word "Unregistered" near the top of the user's /users/[number] page), I add something like:
Do you think we should do something similar here, "rewarding" new users for good questions, and of course also warning them if (as it happens a lot with the [font-identification] tag) they are missing the point of the site?
The 'corrective' comment happens naturally most of the time, but do you think we should agree on a welcome text too, and encourage it as a community?
EDIT: If we agree on this idea, we could remove the spider webs and sweep the floor of that poor chat room we have, and decide on the messages there (Welcome message, font identification boilerplate, and any other ideas).