Are you sure you're not mistaking Trusted Platform Module for Trusted Execution Enviroment which is part of pretty much every modern processor?
Most modern browser-based DRM schemes are based around using the hidden Trusted Execution Enviroment registers for key exchange/decryption etc. rather than the observable regular CPU registers.
TPMs are still pretty rare in the average user's computer and would probably not make sense to use TPMs for DRM unless companies started shipping TPMs by default with the motherboard even though they can be used for such.
