There's "should this be possible" and there's "should this be presented in an easy to access way". Should machines be designed such that it's absolutely impossible for users to modify every single piece of software on them? No. Should machines be designed such that it's trivial for users to reconfigure them in ways that stop them from working? Also no. Nobody ships systems that offer the full range of chipset tweakables in their firmware setup, and that's the correct choice for vendors to make.