Would you have this same reaction if someone said they were creating a social network for programmers? Music Lovers? Runners? Cooks?
Saying that you are creating something that is targeted to a group of people is perfectly fine... complaining that people identify as that group of people seems silly.
I don't identify ONLY as a gamer... I'm a gamer, a Dad, a Canadian, a jr developer, a painter, etc etc etc. If I feel like consuming content about a specific one of those subjects it's useful when they call out who they are targeted for.
You are confusing the use of labels or even self identifying as belonging to those labels with the attitudes of those who are in those groups.
You're taking a vocal minority and painting the entire group with it ... think of other areas in life where you wouldn't do that...
I would say I'm a climber, since that takes up a lot of my time. I will spend 3 evenings a week in the climbing gym and often go to the mountains on weekends.
If I date somebody it's a big bonus for me if they climb, too, it makes scheduling together time much easier.
I'm not a gamer, but most gamers I know spend significant amount of time on gaming, so much so that it often crowds out other social activities (which is ok). If a gamer wants to be together with a gamer the seems reasonable to me.
It's not "every"thing, but "some"thing. It's just a simple patternmatching-mechnism to filter out people who might be interessted in whaterver you are selling. Nothing prevents those people to also match other patterns or even indicate that it's forbidden to match multiple patterns.