Why aren't Jokers a part of Blackjack?

“Thorp said it was impossible for anyone to do that. The dealer insisted that the pit boss could do that—he could memorize the whole deck.” Is it easier said than done when it comes to BlackJack? 

“Kimmel wanted to visit a friend who ran the Primadonna Casino. He instructed Thorp not to use the system there” If someone masters or tweaks this system and uses it now in Casinos...would they catch on as quickly as they do with card counting? 

The Kelly System or Thorp’s System? 

If there is a book/pamphlet on how to properly use the card-counting system, why don’t more people use it? (taking out the factor they will get caught)