Every single one of your points is wrong.
1) You're implying Genji is a monster at low level play because he's a better player not a better character. No shit. They can do it with almost any hero.
2) You're implying Genji's deflect is based on his skill, when in fact its almost always based on the skill of the hero attacking him.
3) Countering picks is how the game is played. Yes picking Winston causes you to be "vulnerable to others", but it also completely nullifies Genji if you can peel properly.
4) His mobility isn't crazy if he's trying to cut you. He's not climbing up walls double jumping when his ult only lasts 6s. He's finding picks and resets which by the way (as a Genji player) is very hard to do on the fly. You have to find your pick (usually mercy if I can), then plan a next pick before committing. If you blow your ult and then just go in swinging you will die EVERY single time with no kills, maybe 1 at best.