Stallman's right, but people don't seem to care, in much the same way that they stand by while their privacy rights are eroded in the name of safety. I am at a loss to explain why people don't care about this.
Part of the reason is that people don't invest themselves in their computers the same way people like Stallman do. As I've gotten older, my computer has just become something I use, not something I'm personally invested in. I don't really care if it's locked down in the same way I don't care that my car is locked down. If either need fixing I just take it to professionals whose job it is to fix it. I really care even less than my car because my car is a lot less easily replaceable.
I made this point in another thread but part of the reason it's so easy to just take your car to a professional is that it's not "locked down".
So anyone with requisite skills, knowledge and tools can fix your car, therefor auto mechanics have to compete on price and service. If your car was locked down in the same way you would be forced to go back to the manufacturer and accept whatever service they offered.
You could argue that this is a bigger problem with computers because they are more prone to monopolies due to the complicated interfaces between hardware and software systems, your car only has to interface with the road.
There are of course other issues too, when 90% of the people on the planet use computers that are almost entirely controlled by a small number of companies and these people use their computers for all of their communication and consuming all of their news this gives those companies a huge amount of power in terms of censorship , evesdropping etc.
So there are issues here that go beyond the computer in itself.
My car is definitely locked down in about the same way as my computer. The hardware is open (though much harder to get to these days than before), but the software is closed and you can't peak inside without specialized equipment.