You're missing my point. How hard is it to learn which hands in poker are best? A child can do that. Learning basic odds in poker is no different than memorizing basic strategy in blackjack. Does it require skill to memorize facts for a test or memorize a poem? This is human being 101 stuff. Anybody with a brain can do it.
Poker is very skill intensive, but it's not the mechanics of the actual game that make it so. It's all about the betting component. Reading your opponent, knowing what reaction you will get based on bets you make, etc. There is a massive amount of skill in that. I'm not downplaying that at all. But you don't win at poker by always having the best hand.
The math of poker doesn't stop at "knowing what the best hands are". You need to know the odds of getting that hand and the odds that someone else has a better hand. You need to know which hands are the best against your hand and which are the worst. You need to know, how those odds change as information is added to the game.
Then, you need to know how these odds translate into betting. You need to know what hands in what position are worth betting on. You need to know how much to bet to maximize your risk/reward ratio given your chance of winning the hand.
You probably need to know a lot more that I don't know about as I've only played poker casually.
I'll agree with you that mechanical depth of poker is relatively shallow (you don't have many choices and the breadth of those choices is rather narrow), but even if "everyone can do it" it still takes an effort (and I think much more of an effort then you are giving it credit for), most people don't make that effort and as such those that do are able to use there skill to gain an advantage on their opponents. Also, just knowing the math, as opposed then actually executing it correctly is a whole different manner and really not as simple as you make it out to be.
Comparing poker to blackjack where the entire decision tree can readily be printed on an index card is really an unfair comparison.