>I own a piece of hardware, so I can do what I want to it.
It's not a feature for you, it's for enterprise/corporations. You might be the user of the PC, but your employer owns it, and they want it as locked down as possible both from you and from other potential bad actors.
TPM has to be there. If you have a machine that doesn't support a high enough version your OS vendor will refuse to give you any support and if you have secure boot disabled the software you try to run might refuse to work. Today, you can disable secure boot and have a degraded experience, tomorrow, who knows?
Then buy a machine without TPM. Or buy games that don't require TPM.
Of course online multiplayer games are gonna have more stringent device security requirements to try to deter cheaters on the PC platforms. Companies aren't gonna mass produce new HW and SW customized to your own individual desires just because you want something else than the masses of consumers don't care about.
Vote with your wallet if TPM bothers you. Otherwise I don't see what your argument stands on.
It's not a feature for you, it's for enterprise/corporations. You might be the user of the PC, but your employer owns it, and they want it as locked down as possible both from you and from other potential bad actors.