I think that the situation is maybe slightly more complicated than it seems at first glance.
To those who didn't read the article: the backs of the cards were not perfectly symmetrical, so by asking the dealer to rotate the cards so that some were oriented one way, and some were oriented the other, eventually they were able to get themselves an advantage by knowing some data about the value of those cards before they were flipped.
Although I guess if everyone knew about this asymmetry (both casino and player), then perhaps observing it would just become a part of the skill aspect of the game?
Really interesting!