It's not at all arrogant in my reading, more like lightly exasperated? They understand exactly what the color scheme is trying to do, they gave reasons why it is naive, and they basically said, "go with God".

As mentioned in my original post, the theme for sure needs significant work and could be improved a lot. I know my way around colour science and typography, but not around UI design at all and I’m still a novice programmer.

I’m glad I achieved my main goal though.

You're making personal attacks because an artist came along, said "here's why this doesn't work," and when you didn't listen and tried to lecture them about the Readme, they weren't moved, because despite the original author's goals, it still doesn't work

The artist isn't being arrogant. You ignored what they said and talked down to them, and they stood their ground. Now you're acting like they're doing something wrong, and publicly criticizing them.

No, it's not arrogance. It's just that you are arguing without understanding.

I've been a professional artist for twenty years. My preferred method of working is to place colors directly against each other without the safety net of hard, high-contrast outlines to save me from the muddy pit of samey values. I have to be aware of this problem pretty much every day of my working life.

I am curious how you think I could have said "dude you are making this so fucking hard on yourself by choosing to have next to no value contrast, here are some ways I regularly have to check that I'm not doing this by mistake, good luck figuring out how to get everything else so amazingly perfect that it overcomes this giant deliberate flaw" without sounding "arrogant".