The question is not stupid or philosophical, in fact it is a very recurring question when you try to sell a product and it enters more into the field of marketing, perhaps that is why it does not seem very useful to you, but it is very important.
Basically the idea is to look for the strengths of your product, for example, look at the war between the SNES and the Genesis and the famous "blast processing".
When you ask yourself the question, you are trying to find the strengths that make your product different or interesting. Of course, this only makes sense when you are talking about selling your product with respect to what already exists on the market, something that many times as amateur creators we do not consider, normally we program games for the challenge or fun, or sometimes, because they are aimed at a very niche audience, which is not covered by other games.
Don't see the question as a way to question whether or not someone is going to play the game, but rather as a tool that looks for the strengths (or sometimes weaknesses) of your product.