And it’ll also be kind of a problem to Plex if they’ll have to battle all those hundreds(?) of streaming providers for bypassing their own web or native clients. While you might get away with that if you’re doing it as a hobby / private person… Plex is a legit company and cannot simply take over the streams of other companies unless they have a licensing agreement (which will cost them money… independent if you’ve got your own membership with a particular streaming provider).
There’s also the aspect that those other providers usually protect their own streams.
TL;DR: Plex have previously stated that requests for provider integrations will be closed.