I don't want to become a broken record, but how is it an example of Apple "locking down what you can do with your own computer" when they also give you the ability to remove the lock?

I truly don't understand why this appears to upset you so much. I realize that disabling SIP is a very minor inconvenience but you've spent considerably more time writing these comments than it would take to disable SIP.

Now, if we were talking about the T2 chip and replacing your SSD, I'd be taking a totally different tune here. There's also a certain other Apple operating system that is considerably more locked down, in very annoying and non-optional ways...