Whenever I do something for the first time, I read the instructions. I spend time to understand the rules and try to follow them in good faith. Yet after having spent this effort, if I am later get told that there were other hidden catches, or some rules buried at a location where I could not reasonably have looked at, I get really upset. I know other people are just ok to jump in and make mistakes and don't mind getting corrected later. But for people like me, not having been told the rules in advance is an easy way to get put off. Besides it is a waste of time for me and those who end up forcing me to do a correction.
In this spirit, I would like to propose an improvement to the system-tagging requirement. Please have a look at the screenshot for asking a question:
While not tagging your question is likely to get your question closed, there is no warning about it. Even when you click on the question mark to get help about "How to tag", you don't get an explanation.
To make matters worse, a responsible user might see the "Helpful Links" box on the right side of the page and decide to click on "Find more information about how to ask a good question here". When they do, they are directed to the following page: https://rpg.stackexchange.com/help/how-to-ask
Yet there is no mention of tags there either. There is not a single sentence stating the utmost importance of properly identifying the system your are interested in, for questions that pertain to individual games. (Not just in tags, not anywhere.)
We could argue that identifying the RPG is something that needs to be done by default and that it should be obvious. But apparently it isn't, given the almost-religious conviction of a considerable number of experienced users about the never-guess-the-system policy.
Could we please try to rectify this situation? Seeing the importance of tagging the system right away would significantly decrease this pitfall, and perhaps we won't need heavy handed solutions like the strict never-guess policy.