Even so, on most of the platforms you list you can disable the security checks and attestation mechanisms with a custom OS, which mitigates the risk of letting a site know that your computer is running any specific version of an OS with the proper anti-tamper checks. If you find a device that doesn’t, you can just not buy that device. At a certain point it’s not constructive to say “you can’t build that” when there is enough of a consumer benefit/desire and business incentive to do so.

But you can still get computers that have none of that stuff, or where it can be disabled.