I think you might be misinterpreting the advice in this short article. This is advice for managers for their interactions with subordinates, not for subordinates in their interactions with superiors. The advice states that their very position of power may give undue weight to their casual opinions or observations.
I think it's clear that this isn't suggesting withholding of all feedback when appropriate. It's saying that a casual, "I like blue" when the design being presented is purple isn't really helpful. If the boss has data that shows that actually blue increases conversion by 5% then it is not just this "two cents" that the article is talking about, it's an entirely different conversation that doesn't fall under the scope of this article.
I think it's clear that this isn't suggesting withholding of all feedback when appropriate. It's saying that a casual, "I like blue" when the design being presented is purple isn't really helpful. If the boss has data that shows that actually blue increases conversion by 5% then it is not just this "two cents" that the article is talking about, it's an entirely different conversation that doesn't fall under the scope of this article.