Right. No one is keeping you from putting on a pair and taking a skate on the bike path. And, once in a great while, you see someone doing just that. But there's probably no skate rental place on the bike path any longer, people don't organize group trips, and there are no mass urban Friday night skates.

I assume while frisbees are still around, they're also seemingly much less ubiquitous than they were.

Frisbee golf isn't all over your public parks?

Never seen it locally--not that I really have much in the way of public parks where I live. I was mostly referring to the fact that it seems you just see fewer people playing frisbee casually than you used to. (I did and I've never played frisbee golf in my life.)

In fairness, I'm not really sure frisbees are a fad. They've gone through peaks and valleys of popularity but they've generally stayed around in some form.

This is a bit odd, both Disc Golf and Ultimate have "gone pro" with professional leagues some of which is even broadcast.

That may be, but I live in SoCal and I seldom come across disc golf parks, too, let alone anyone playing it. And I know someone who plays on a team, though he lives hundreds of miles away, in Santa Cruz, where I understand it's more popular.