MA.SE FAQ has a point in don't ask,
If martial artist A would beat martial artist B (not constructive)
Linking to Gorilla vs Shark, now on the surface it looks like SE has made a clear stance on X vs Y questions, and that's even about a fight, but applying that to MA.SE doesn't make sense. Martial Arts are inherrently about two people fighting each other and one person winning (protestations of people who say MA aren't about fighting notwithstanding), and you do actually regularly have Martial Artist A fighting Martial Artist B.
Let's look at the reasoning behind Gorilla vs Shark, and let's see how it doesn't actually apply to Martial Arts. We'll do Chuck Liddell vs Mirko Filipovic, as that's a fight that hasn't happened, but a lot of people were interested in in the past.
Nobody needs to know the answer to this question.
Strictly speaking, who really needs to know the answer to any question that's asked on MA.SE? You could certainly go on with your life not knowing the answer to the question, but if you do know the answer, it could turn out to be quite illuminating.
It’s not nearly specific enough.
We've already got a lot of the concerns covered given that you can reasonably assume under what conditions a fight between two professional fighters would take place - the scope of Martial Arts as a topic automatically provides context for an X vs Y question that isn't available without elaboration within a different topic. There's still a question of UFC Octagon vs Pride/Dream/Deep/K-1/etc Ring, but those differences actually make up a pretty interesting discussion.
First, you've got the surface. The Paint/Canvas combination used by the UFC and other Unified Rules promotions is different from the Paint/Canvas combination used in Japanese MMA promotions. Under Unified Rules, the canvas is slippery while the decals are sticky. Conversely, in Japan, the canvas is sticky while the decals are slippery. Since there's much less surface area for the decals than the canvas, that's the difference between fighting in a parking lot with small patches of black ice vs fighting on a recently washed floor that has had some patches dried up.
Stylistically that plays a big difference. You want to have a grippy surface if you're going to be throwing high kicks, so under Unified Rules, one part of Mirko's double threat (his LHK) is neutralised.
Now is that relevant to anyone else? Actually yes, some people actually do train MA for the sake of professional or amateur fighting, and even outside of that, if you've got a high chance of being on slippery footing, you don't want to make high kicks a core part of your fight strategy.
The shape of the competition area is also relevant. With the larger area, and being bounded by an octagon rather than a square, under Unified Rules you can't corner your opponent (literally). That's something Mirko made great use of in his run in Pride, but is fundamentally impossible to do in the UFC.
Again, relevant to anyone considering a career, or even hobby, in MMA. It's also relevant outside of competition, you don't want to rely on being able to just move laterally to escape an attack given you could very well be in a room with right angle corners.
It is difficult to learn from these questions.
I already addressed that, there is useful stuff you can learn from these questions, as long as you actually analyse the situation critically instead of just throwing out an opinion. Unlike the Gorilla vs Shark example, information that you learn in comparing potential fight outcomes is quite relevant to people who are considering fighting.
It drives away experts.
Hell no. This is the type of question that attracts experts. Jack Slack's analysis of Edgar vs Henderson They're not going to decisively answer who will win, after all that's why we have a fight. They'll analyse factors that have to be addressed, and who needs to make more adjustments going into the fight in order to increase their chance of winning. There are a ton of Jack's articles on various sites doing Fighter vs Fighter Analyses. See here
It might be better to word the question as "Who has the advantage in a fight between A and B", but fundamentally the question remains the same. In fact, it's merely a future speculative version of;
Analysis of tactics and strategies from historical competitions, tournaments, and sparring matches
Which is in the type of questions you can ask. In fact, we've got a big problem in the FAQ of having the "type of questions you can ask" having significant overlap with "type of questions you can't ask". Asking what could happen in a future fight wouldn't be all that different from asking what a fighter might have had to do in a past fight to change the outcome, but the scope of stylistic match ups and questions that can be asked can be expanded beyond fights that have actually happened.