What I heard (on here, and I hope it's a vicious rumor) is that TPM 2.0 comes with backdoors accessible to Microsoft via the OS so that a significant chunk of the computer belongs to Big MS and not to the end user, and it will squeal and cause problems if the end user tries to take it back.

The whole point of TPM 1.0 hypothetically was to allow a larger secondary encryption key of a device to be accessible only by a small user-provided key (say a four-digit PIN), and requiring use of the key-query software to run to get the secondary key. A limited number of chances with longer delays with each wrong answer heightens security.

But this pissed off government law enforcement across the world, who want backdoors for when they want to crack the phone of a very important criminal.

It would be nice if Apple, Google and Microsoft had more respect for their end users than they do national and corporate institutions, but we know this isn't really the case, so it's at least plausible that TPMs 1.0 or 2.0 come pre-backdoored. It doesn't hurt that this is exactly what FBI and NSA want even though (Pre-9/11 and Pre-PATRIOT) NSA is supposed to be assuring that no-one, not even police can crack our secure communication protocols.

Despite efforts to look into it, I've yet to get an answer I can fully trust whether or not they are backdoored. But since Microsoft is notorious for exactly this kind of bullshit since the 1980s, I assume it's true that TPMs are backdoored until I find convincing information otherwise.