Note that these aren't wild guesses being made: they're not “this person mentioned wizards, it's probably D&D 5e”, but instead educated guesses or inferences made based on the content of the question we do have. Taking the most recent example cited just earlier today, our users' guesses were based on an exact quote and page number from the PHB lining up with the D&D 5e PHB—and those inferences were correct.
The main pragmatic reason remaining to enforce this policy is because it requires people to learn how to use the site before they can get answers.
I'd like us to examine this policy as a community, consider our options and the pros and cons, and work out what we'd like to do from here on. That could be a modification or it could be continuing with the policy exactly as-is, whatevermodifying it to be OK with some level of inferences—whatever we choose is valid—butvalid, but I'd like us to choose it because it's what looks like it should work well for us now in our current circumstances.
Given a fresh look: what do we want the policy here to be? How should we approach the idea of guessing the game system someone's using when it's unclear? If we're OK with some level of inference, what would that be?