Let's say there's a channel that churns out a lot of content, but I am only interested in a subset of it. That content cannot be made into a show, as per some YouTube guideline or whatever, but the channel owner helpfully compiles it into a playlist.
I know it's possible to subscribe to a show, but what about a playlist?
(I actually remember doing so about 3 design iterations back, but I can't find it now.)