Only by your definition. Colorless was always about DX, nowhere in the original article did anyone care about implementation. And this stuff does matter. I have created libraries which provides calls in both sync and async contexts to the same function and it works just fine.
Actually, it's not... since you can use it on async and non async functions alike, which is what GP says. PLs with colored functions can't do the same thing at all, moreover the virality of @asynccall terminates at the point where you use it; if it were colored, the context of @asynccall would have to be async, and its parent and grandparent, etc.
