Yeah, makes sense, and for sure works for many cases. But there's no meaningful distance between two sets of preferences that have a null intersection.
I've come across this just as a user with regard to film. I reckon that I've watched all of the 10/10 mainstream comedies that have been made in English. I want more 10/10 comedies, so I'll have to look at foreign languages films. But there isn't enough overlap of user preference, due to demographic separation I suppose, to get decent recommendation from other countries. If you start adding metainformation preferences (e.g. must not be in English, must be >9/10 stars etc) then you're back to Content-based recommendation territory (i.e. audio analysis as Spotify are doing)
I've come across this just as a user with regard to film. I reckon that I've watched all of the 10/10 mainstream comedies that have been made in English. I want more 10/10 comedies, so I'll have to look at foreign languages films. But there isn't enough overlap of user preference, due to demographic separation I suppose, to get decent recommendation from other countries. If you start adding metainformation preferences (e.g. must not be in English, must be >9/10 stars etc) then you're back to Content-based recommendation territory (i.e. audio analysis as Spotify are doing)