Software that requires configuration to be useful to more than one person has failed it's mandate in proportion to that configurability. It's precisely the opposite of necessary glue, it's duct tape: often the pragmatic choice, but almost always a sign of a design failure.
What utter tosh. People have different preferences because people are different. If your point was apt then this submission wouldn’t exist because $SHELL wouldn’t be a configurable option in the first place.
People have different preferences, but moreover people have different needs. Configuration shouldn't be thought of as optional. If, as the parent comment says, settings are design failures, they arise from the fact that it's not possible to design software that works for everyone. To fix this problem you wouldn't have to design better software, you'd have to design a better human!
Just to state the obvious examples, i18n is exposed through configuration, accessibility features are configurations. These aren't optional parts of a program that can simply be designed around.
To be clear, I agree with you that human preferences are valid as such, just clarifying that your parent comment is profoundly wrong even if you think that all people ought to have the same preferences.
Is that true for ... anything at all, though? Outside of computer programs, where you claim it is? The ideal food, the ideal movie, the ideal vacation, the ideal video game, the ideal body, the ideal sofa, the ideal tree...
Choice arises because humans are different, and want - and need! - different things.
There is no ideal food. There is an ideal shell. The difference is that the goals of a shell are well defined, and invariant to human preference. Human preference is real! But when it comes to computer systems it's rarely the correct variable to be maximizing in the optimization equation. The most wonderful property of humans is that we are adaptable: if a circumstance requires us to think of things in a model that isn't our intuitive choice, because the nonintuitive model produces better outcomes by the meaningful metrics, then we are capable of doing that! Our preferences are not these sacrosanct things that dominate the design calculus. They can and should take a backseat to other things when appropriate.
