You gotta be joking? Do you get kick out of casinos for card counting? Yes, then it does work… lol.
People teaches it because it’s hard to constantly make profit at casinos when they will eventually ban you as an AP. Nothing wrong in teaching and having more people learn it. More AP will irritate casinos and maybe that is what someone wants, especially if that person already has been kicked out and/or banned by casinos.
I’ve done it a few times but drink too much at the tables so will lose count (that why a prefer craps). A friend does it but the several things he has to do to stay under the radar is too cumbersome for me. It works but difficult to not get caught and make a profit in the long run.