The advice page seems like it could be a pretty powerful tool. When it is enabled (available by request), it is shown to new users. It also forces them to check a checkbox before proceeding (which you can see here by browsing incognito).
However, I don't really like the page as is. The whole page reads like a suggestion ("thanks, I will keep these tips in mind when asking"!?), none of the advice is specific to the site it's on, and it's a little too long for my taste. I want that page to focus on the most common off-topic questions, with links to more in depth explanations on the site's meta. Therefore, I think it would be beneficial to be able to rewrite the entire thing on a per site basis.
Assuming it's not already possible, can moderators be allowed to edit this page? I think moderators specifically need to be able to edit it because it will make it easier to make small edits to the page.
This would very useful here on MSE because there are only a few rules that tend to trip people up here.
We could keep it short (to maximize the number of people that read it) with only two or three bullets, such as one saying that only questions about Stack Exchange are allowed (and NO PROGRAMMING or MATH questions allowed) and another with instructions on what questions should be posted on local metas. (Together these two points are ~58% and ~7% respectively of the recently closed questions here. Duplicates account for ~27%, which would—in theory—be helped if we keep the search bar.)