You can ask real, relatively specific questions (and answer them)
Quoting from Brian Ballsun-Stanton's answer to "I want to write a Q&A: how do I go about doing that?":
Find real, specific, questions and answer them.
We're not a blog nor a monograph publishing service. When pondering self-answering questions (which we encourage) remember that the questions should be real questions that stem from problems you've seen or are having.
Essentially, the purpose of the post should not be just to advertise the RPG system. It also needs to be an actual meaningful question.
In particular, the method you suggest:
I had the idea of posting a Question about system identification, then answer it myself, given potential readers some information about that system, and maybe make them want to try it out.
...seems a bit iffy.
Specifically, it sounds like you're proposing asking a system-ID question and then answering with some fluff about the system, rather than asking a genuine question about an issue you've faced within/regarding the system itself.
If you're lacking clarity on a rule within that RPG (or you were confused, but figured it out yourself), ask that as a question - and self-answer it if you think you know the answer. If you have a problem you've faced while GMing the system and need help finding an effective solution, ask away.
But as wax eagle puts it in this answer to "What should I consider before posting a question and answer it myself":
Just be sure you put some work into the question itself. My biggest knock on this kind of thing is that people will often half ass the question so they can post the answer. Both should be of quality.
If you don't have a real question/issue to ask about, the quality of your question will usually suffer for it.