There aren't really any mainstream DRM systems that use a general computing platform TPM, precisely because they have a terrible track record of being breached.
The point isn’t to store keys in the TPM. The point is to ensure you’re running an unmolested version of Windows that will enforce whatever security controls the DRM maker wants to have.
Part of that is things like:
* Don’t load an unsigned (or wrongly-signed) GPU driver, because it might be modified to allow a user to read from framebuffer memory after content has been decrypted.
All this effort for nothing making life difficult for the end-user. Physical video splitters are a thing. They are asked to respect HDCP, but they don't have to. It's how streamers are able to play a game on their monitor while also streaming the video of them playing the game.
Oh, no argument from me there, I’m just pointing out that you kinda need TPM to make your DRM not trivially bypassable.
I imagine that the MPAA et. al. are planning to attack the splitter thingy one day, so they’ll want to make sure you can’t slurp the frame buffer when that avenue is gone.
