Maybe that's today's true counter culture; anti-consumerism and switching offline. Thousands of people do it daily - delete their Social Media accounts, stop sharing everything online, stop watching endless video streams, stop playing meaningless games, and just escape the marketers trying to make a quick buck from their identity. You're not worth targeting if they can't sell you anything. It's the first "silent" counter culture.

It's not that it doesn't exist. There is no "dark corner of the room" dynamic like you had between punk and the nuclear family; more like, it's a different room altogether, and the other cultures don't get to see what's in that room. It's a society where the culture and the counter-culture don't share the "town square" together like they used to as much.

Alternatively, like you mention, it's existing in a different digital sphere to the mainstream. This can be intentional; using alternative forums like Mastodon instead of Twitter, Discord instead of Facebook, or whatever alternative it might be. IRC chats and email threads are still going to this day. It could also be unintentional; two people can be using YouTube but have completely and utterly different feeds and comments that they interact with due to an algorithm.

These alternate realities never really existed to the degree they do today. Previous cultures had the ruling and working classes, or ruling, working, and slave if you go back far enough. Stricter class boundaries, but within those classes things were more homogenous culturally. Less people, that meet in the same forum, pub, feast hall, or religious center. Now, the lines between classes are blurred and the classes themselves less homogenous. More people, more meeting places. More things to build an identity and culture around. That dilutes the predominant counter-culture enough for people to ask whether it exists at all.