I'm going to be totally honest and say that the concept of gamer culture kind of makes me uncomfortable--kind of in the same way that sports culture makes me uncomfortable.
It's not the people that participate in the activity only as a hobby that bother me though, it's the people I've known who maybe don't have as much of a real-life connection to go back to, you know what I mean? The really hard-core sports folks kind of make me feel the same way--they seem to latch their whole identity around following some games, but when I talk to them and that's all they really have going on in their lives, it all just makes me feel a bit sad.
I somewhat agree with you, but here is a counter question. As someone who probably has to work from morning to evening (nowadays sometimes more), for how many hobbies do you even have time? There are more and more people in this age who between work and maybe raising their kids really don't have time to engage in any hobbies anymore. Even having just one hobby seems like a luxury to me.
So while it would be awesome to game, do two different sports, go traveling, play an instrument, romhack and read high literature and go to the theater, who the hell has time for all of that? Realistically, it's pick one or maybe two if you are lucky.
Of course it's a different story if we are talking teenagers who have half the day any day and do nothing but game. But hey, they are teenagers, they do pointless stuff by default. I nowadays wonder what the hell I did with all my time back in the day.