If it's useless for you, then you can ignore it; I don't really care one way or another, nor do I have a horse in this race. I find the whole blue/white shirt thing easy to think about and apply, and it's proven relevant to my wardrobe. So I like this particular guideline.
And that's fine. Acting as if it's a truism that's broadly applicable isn't. It's a shortcut to your personal preferences, but it hardly defines appropriate attire, nor does it steer you away from bad choices towards good ones- it steers you from good choices to other good choices. Which is useless.
The problem with stuff like this is that it leads to groupthink- it hardens in people's minds until what is properly a shortcut for one person's preferences gets cited as a hard rule. That's a big problem with these online menswear forums- the preferences of a few people are heard as gospel truth. Think black suits here- the idea that lounge suits should not be black has very, very little historical support. It was a pretty common color in the past- at times, THE predominant color. But some people's opinions based on its somewhat limited versatility in shirt and tie pairings and problems with some skin tones morphed into a consensus of 'nobody should wear a black suit ever'. I don't think that's a good development, and that's what I don't want to happen here.