Grumpy cat is mainstream culture. Yes, just because something has been widely consumed does not make it impactful, but that's a very different position from there are no impactful things widely consumed.

The impact of various past countercultures is only evident in hindsight. As you said, movements like the Beat generation were at the time tiny subcultures, of the exact same sort we have loads of today. To say that 80s hackers were a counterculture but modern biohackers are just a subculture is simply temporal chauvinism.