Plus, what is Netflix even going to do? Stop supporting streaming on Microsoft platforms and then lose a bunch of subscribers for no benefit to themselves?
Also, the issue is that somebody is going to copy a ~30 fps video using screenshots without audio taken at an interval of ~0.2 fps? Nobody is going to do it that way.
The promise of DRMed content at the moment is that (technically) no one is able to do so as there are no backdoors into it, for nobody.
What happens outside of that path, before it's decrypted or after it's displayed, is beyond what DRM is meant to control.
In order for the device to display the content on the screen, some part of the device has to have access to the plaintext. That part of the device is controlled by Microsoft -- it's their DRM system, they wrote that code and have the keys to update it -- so they inherently have access to it. Saying "that part is outside the scope of the DRM" is just defining your way around the fact that they can still do it.
Or to put it another way, if some court orders Microsoft to extract some DRM-protected content, what do you think happens?
So while Microsoft controls the platform, that doesn’t automatically mean they can trivially extract plaintext content from DRMed streams, especially not without compromising the integrity of systems they themselves may not fully own.
And even that is assuming there is no way to remove the watermark, which there always is because multiple copies of the same video can't each be uniquely identifying without revealing what's different about them.
Meanwhile the inconvenience to paying customers is real when their stuff doesn't work, and every customer who pirates your stuff because the paid offering doesn't work for them is an actual lost sale.
It really does seem like the DRM vendors are taking them for a ride.