It is generalizing, but I don't think the intent is to be dismissive even if the end result might be. I find myself saying all pop music on the radio sounds the same which is why I prefer to listen to more obscure stuff from other genres. However, to my wife and kids who actually enjoy the pop music on the radio they feel the pop music is diverse and it all has unique sounds.
That's just how it goes. Where your interests are strongest your view of the picture become the most detailed and you see a lot of diversity, where your interests are weakest you are seeing the picture in a more generalized, zoomed-out, manner and you will see things more grouped and similar.
It feels kind of weird to see this sort of garbage here, in what I normally see as a mostly supportive creative community.
By now you should know that this community also excels at hyperbole. If you take
Gimmy's comment literally it might sound negative, but if you just look at the general sentiment he is pretty much saying he misses the days when experimental games held the spotlight. It's an understandable feeling.