Hostile? I would call it "fair". Because, ok, let's assume you win. I'm wrong, you're right, and some ultimate dictator decides that all websites now are coming in black-on-white only. What should I do, as a person that feels low-contrast is much nicer than eye-burning one? Exactly, I'm about to make my own customizations or suffer. And then you should be saying, that black-on-white is hostile to me, which wouldn't make much sense, as you (or somebody else for that matter) would have something to complain on either way.

Hence my first point about "if it hurts conversion/…". In other words, if it's your business — it's your business. If it's not — well, you are free to complain about other people coloring their stuff as they like all you want, but I hope they won't be upset about that, because they really shouldn't be, and believing that your point of view is the only right one (even if it's supported by some Nielsen or whatever) is simply ignorance.

I agree that too high contrast is also wrong. Notice how the submitted website does not use black text on a white background anywhere? No one is asking for maximum contrast. People are asking for good contrast, and that includes "not black on white".

Do you have visual trouble reading books also?

Your monitor brightness maybe set too high For example, mobile devices' minimum brightness is far too bright in a dark room.

Asking visitors to make adjustments to their taste is far easier and less hostile than asking a webdev to create a webpage which uses colors that every person who visits it will like. In fact, it's not just hostile to the webdev, but impossible.

But I'm not asking designers to guess what visitors will like. I'm asking designers to avoid a narrow range of colours that we know people hate.

There is no reason to use light grey text on a mid grey background for text that you want people to read.