In one of the other threads asking about a “disable” option, a couple of Plex employees said that showing the other services was an intentional decision. Selecting “your” streaming services just puts those higher in your search and Discovery lists.
It’s a terrible decision, but they don’t seem to care.
Edit: Surprise, surprise. In another thread in response to:
Elan said: AFAIK this will be in an upcoming update.