[evo]

My take is that this (and similar effects in other media) is the consequence of the rise of targeted advertising. Prior to the advent of surveillance capitalism, there was a vested interest in the development and refining of subcultures.

Someone in the media would identify a new nascent subculture, invest in catering to it, and in the process create a new demographic that advertisers could pump money into to address a specific audience. Ugly and capitalist, sure, but on the flip side, if you were a member of one of those subcultures, there'd be a steady flow of investment into the community you considered yourself a member of. If you listened to the Grateful Dead, someone would be there to sell you peace signs and tie-dye shirts. If you listened to emo punk, well, Hot Topic. The money the advertisers paid would go back into the magazines, critics, studios, etc. that would then further promote, develop, and refine the subculture--a virtuous cycle of sorts.

Google et al. negate the need for any of this. If you want to sell tie-dye shirts, you buy a slot on the "tie-die shirts" keyword. It's (arguably) more efficient for the advertiser, but, it eliminates the economic incentives for subcultures to exist. So they don't. Everyone is their own one-person-addressable subculture, which is essentially identical to one sprawling morass of culture.

What little money remains flowing into the media system chases the spontaneous flash-in-the-pan meme hits that broadly appeal, because that's all that's left.