As someone who used windows for way too long: they just simply don't give a shit. Like at all

If you're not the only one with the keys, is it really encrypted?

i saw your dog using arch linux

Why do you think the encryption capabilities on your PC are there for your sake? They might have sold them to you on that, but they are really there to protect copyright data because TPM allows encryption/decryption that is completely hidden from the rest of your system. Like an encrypted handshake that then transfers an encrypted key to decrypt the video stream. But it doesn't save the decrypted data, it immediately re-encrypts it using your display's private key (or whatever device is next in the chain, maybe your GPU). They can make it so that the unencrypted stream never touches your RAM or travels on any wire, which means you can't pirate shows as you watch them unless you point a camera at your screen.

Obviously if they just said that was one of the main points, no one would want it and media companies couldn't benefit from it because they'd have to compromise to sell content.

The other point was so that they could build a system where they hold the encryption keys and get to choose whose data is actually private. Obviously that's an even harder sell.

So they did what marketers always do and lied by omission about what it was for and just outright lied if they ever said they'd never give the keys to law enforcement (did they ever even say that?).

Let go of the idea that someone selling something to you implies any kind of loyalty, especially when either party is a large corporation.