I find it's pretty easy to put a link in a comment to the on-topic help page and possibly a related meta post (or canonical question, such as for the licensing questions).
A great deal of these off topic questions are covered by the bold text near the top of that page. If someone can't even be bothered to read that far (or click on the help link in the first place), I'm not sure another help page (even one that is more concise) will help them.
That said, people are known to skip FAQ pages with alarming regularity no matter how easy you make it, so a proactive solution is hard.
It would probably be a better strategy to use javascript to shove the on-topic help page in people's face gently introduce people to the purpose of this site the first time they try to post a question. An abbreviated version of it might be suitable for that purpose.
If, after being shown in bold text that our target is IT professionals looking for help with their professional environment, people still ask us how to reset their password configure their ISP-provided residential gateway or whatever, I submit there is nothing we can do except comment to them and delete their question. However, we do need to present the core of the criteria as concisely as possible.
We could probably make such a prompt look a little like this:
Welcome to Server Fault!
Server Fault is a site for system and network administrators needing expert answers related to managing computer systems in a professional capacity. We most appreciate questions that have a single right answer and indicate that you've done at least some research into the problem on your own. Provided that your question is of that nature, we would be delighted to help you out.
That would filter out a great deal of the problematic questions while being extremely concise (but hopefully not terse).
We could also be a bit longer:
Welcome to Server Fault!
Server Fault is a site for system and network administrators needing expert answers related to managing computer systems in a professional capacity. Provided that your question is of that nature, we would be delighted to help you out.
Some things which are within the scope of this community include:
- Server and Workstation operating systems, hardware, and software.
- Business/Enterprise grade virtualization
- Enterprise storage, backup, and disaster recovery
- Network routing, switches, and firewalls
- Operations, maintenance, and monitoring
If you are unsure whether your question is on topic, please take a moment to read through our help page http://serverfault.com/help/on-topic. Otherwise, you're in the right place - ask away!
This might be better than the original solution (before the overhaul) of pointing new users at the FAQ page, because at least everyone will have seen it.
We could also write a proscriptive blurb, but I'd prefer to avoid that lest we appear hostile.
Needless to say, I think the on-topic help page is really the key to mitigating this issue. We need to gently make it very clear that this isn't merely an advanced mode of SU.