The most important thing is to default to the user’s system setting.

Then you (and your users) only need the toggle, if at all, for edge cases.

(If the user cares, they likely will have set system settings the way they like them, and if they don’t care to, it’s pretty unlikely your web site is special to them. It would really just be for users who care but are somehow forced to use a system that doesn’t support the settings they want, and for dev/testing.)

But I agree with the conclusion of the article. If you do have a toggle, it makes more sense to just have the two options. Users click it to say, “I want it the other way right now.” After that, it makes a lot more sense to assume they want it to keep being the way they want than not. And how do you know what that is? Because they’ve taken the time to specify that in the system settings. Or they haven’t. Because they didn’t care to. In which case you still aren’t doing something they didn’t want.

A UI where you just whack it until it does what you want (and then keeps doing it) is perfect for we tailless monkeys. One where you have to stop what you’re doing to think about your previous life choices and whether you ought to continue to make them is maybe a little too much for each web site.