That article has actively harmful advise for people who have my type of color blindness (red deficient and green at the wrong wavelength). Their advice for red-green color blindness is basically to only use greens and yellows which are pretty much impossible for me to tell apart.

The best is when people make sure there is something other than just color to tell something apart. If you are making a game, the best is to have a color wheel to pick the colors for things (UI elements, friendlies/enemies, etc) as most forms of baked-in colorblindness support tend to just make things worse for me.

Where is the recommendation for using green and yellow? I can't find that.

I understood the recommendation to be 'use extra visual cues', except when only 'color contrast' (basically two contrasting-brightness colors, and the color itself has no significance) is being used. I'm colorblind too and totally agree.

They have color charts for each type of colorblindness with lines drawn on them for sets of hues to avoid. None of these lines go through both the green and yellow colors.

That is not in the article itself, is it one of the sources linked?

I am red-green colorblind and I actually thought the article nailed it in my case. Don’t depend on differences in hues, but use differences in contrast (saturation and brightness). If UI folks followed this rule I’d be good.

Aside: Last time I was in Spokane some genius decided to turn the light signals sideways. I had no way to tell whether to go or stop w/o watching other.

I think that's the point the person you're replying to is trying to make. The author nails it for red green color blindness, but fails for most other forms of color blindness

I've never understood if there are really people who commonly confuse red and green, or if others are making that assumption because it's commonly called "red green color blindness", but that assumption seems so ubiquitous, it makes me feel like I'm misunderstanding something. I'm red-green insensitive, and in reality that's exactly how it manifests, not as the inability to distinguish red from green. It's what you'd expect: Purples look more blue, greens look more yellow. That's (mostly) it.

Yep, they exist. I'm one of them.

When you see either red or green in isolation, does it take you longer than usual to tell which it is? It does for me. It's pretty rare that I simply can't tell at all, but it does happen, and it's common that it takes me multiple seconds to figure out which it is. The little red/green leds that the sibling comment mentioned can indeed be particularly shit.

The purple thing sounds familiar to me. If you take blue and add red or green, it can be very difficult for me to tell which it is. That was my earliest issue with colors, I got in trouble in school for mixing up bluegreen and purple.

There do exist some pretty detailed tests for exactly which type of colorblindness you have if you're curious, though I'm not sure if they can be done reliably on a non-calibrated monitor.

There definitely are people who confuse red and green, I know one. He really hates all those battery chargers that change color from red to green when they finish charging because he cannot distinguish them at all.

When 'color contrast' is mentioned he is referring to the example with the toggle tokens, with widely different brightness for the active (blue) and inactive (light gray) states. I suggest re-reading the article, since the author agrees completely with you - your last sentence is a straight paraphrase of this:

> If you’re using competing color hues to differentiate states, you need another visual cue besides color. But if you’re only using color contrast to differentiate states, it’s likely accessible to color blind users.