That post was made by a sperg. The funny part is he actually accidentally acknowledges why the style is useful in certain cases, but is so emotional that he pretends that those use cases are actually evil for daring to exist>>106920396
John K made a post about it that I actually agree with; they're too abstracted from real life to make actual characters.
A flat, geometric representation of a man will immediately be registered as a man at a glance. There is no ambiguity at all as to what it is so your brain isn't hung up thinking about said man and can move on to the rest of the information.
But the flat symbol for a man will never be a specific man. Your brain simply doesn't know enough about him to sympathize with him. The style lends itself great to adverts and informational videos, but is awful for telling a story