The public appetite for genres comes and goes — superhero movies were big in the 90s, too — but I do think you're right that the recent development of "everything (mostly), all the time (mostly), on-demand (mostly)" availability of content at least partially confounds this cultural rhythm. My kids are nearly teens and have never intentionally listened to radio, which drove and reflected popular music tastes when I was a kid.
Although there are still certain broad pop culture phenomena, it is certainly a much more fragmented landscape than it used to be. I'm very aware that I'm pretty ignorant of the current music scene for the most part. When I was still going to large tech events pre-COVID, I definitely started seeing bands at parties that I had never heard of (and mostly wouldn't listen to by choice).
And while I watch some shows that are on the pop culture radar to a greater or lesser degree, I'm not necessarily watching them when they first hit streaming. Certainly there's very little that's the equivalent of Must See Thursday on NBC where most(?) people were aware of certain shows even if they didn't regularly watch them.
