There's a boatload of boards that don't discuss politics or news and aren't viral marketing wonderlands, so basically you guys are choosing to subject yourselves to that stuff.
I'm more bothered by the endless cynicality and aggressiveness of imageboards, but I don't think it's really a new trend, I've just grown out of imageboards. Nowadays stupid Youtube gaming videos entertain me way more, because the people in them are having fun.