The reality of it is, is that card counting is very simple.
Card counting perfectly, in any situation, under any circumstances, with surveillance from the cameras, dealers, and pit bosses putting heat on you, being asked questions by the waitress and other players wanting to make small talk, converting the true count after keeping up with the running count, and all the lights, bells, and whistles of a casino environment all while trying to make it seem as if you're not counting (in demeanor and by your bet spread)... Is very difficult.
Oh, and lest we forget the most important aspect of card counting is being able to memorize and execute perfect basic strategy under all the said conditions.
That's the only reason to learn card counting in the first place is so that it will allow you to take maximum advantage of playing perfect basic strategy.
If you don't know perfect basic strategy then card counting does you no good, at all, whatsoever.
You have to commit this entire chart to memorization and play it... perfectly...while needing to also know the 18 different variations when you need to deviate from basic strategy.
Again, I stress one does not need to be a genius to do all this... but it takes an extraordinary amount of dedication to achieve such mastery that most people aren't cut out for it.
That's not a knock on most people, that just shows how difficult it is.
Not to mention that you would also need to keep bankroll management in mind as well. Maybe you can learn to do all of the above with 100% accuracy, but if you don't manage your bankroll correctly, well... you can't gamble when you're flat broke.