Why? To satisfy people’s preconceived notion of what a gamer is?

You can definitely break the industry down deeper by looking at different cohorts which is interesting but doesn’t alter the top line numbers.

I have never heard the use of "gamer" to mean "at least plays games sometimes every now and then".

You can understand though that from a broad industry perspective everyone that plays games is a potential customer and thus interesting as a gamer?

Yes, in the same way I am interesting as a carpenter.