I don't use Spotify, and maybe I'm just old, but I hate every platform having their own way to communicate. Especially when I want to look up something later I have to search in 4 different places and hope their search isn't terrible. There was one short period of time where Gaim/Pidgin/Adium worked.

I understand the benefits, but I feel like the main reason these are viable is because email was ruined.

Agreed, and outside of the pure messaging aspect, it was a great way to quickly share music in the same place you were going to listen to it.