I think it's worth noting that the TPM plans of 2003 differ a bit from TPM-as-of-2018.

What was called Trusted Computing, Palladium, TCPA, etc. in 2003 and became known in geek circles as "TPM" is now implemented as TPM + Intel Boot Guard + Intel SGX + Authenticated Code Modules + various other things (and other vendors' equivalents).

The TPM is the most benign part of it all: a slow, passive crypto chip with a small storage that it can hide away from the CPU unless the right system state and keys are presented (although the presented system state might be 100% fake).

Cr50 is quite different from the Infineon et al TPM item commonly found in x86 boxes. It is able to rewrite AP and EC firmware, overriding the advertised write-protect feature; access the microphone; etc.

No reason to take my word for it: I recommend to read Google's source, I have linked to the most interesting routines.