Originally, they were going to support Amazon (who offers more storage as part of Prime), but that was dropped at some point. Those cloud providers likely don'

Originally, they were going to support Amazon (who offers more storage as part of Prime), but that was dropped at some point. Those cloud providers likely don't want to get into the business of hosting media files that go into Plex. There aren't a lot of legal ways to get TV shows and movies (the bulk of the space) into the DRM-free format that Plex needs.