Its because Ronaldo is a machine, he doesn't have pure moments of genius like Ibra, Messi, Suarez, Neymar hell even Bale is more inventive than Ronaldo. He doesn't do anything that other people can't do besides run hella fast and jump hella high which is purely physical. He is much more of a world class athlete than a footballer.
+100
For all the theatrics and razzmatazz that comes with the Ronaldo show, when the game is on the line, he usually goes missing. He's had a couple moments in big games but for me, the best players rise to the occasion when their team needs them the most, and I honestly can't recall a game in which he was truly the difference in a tight match against a world class team. He rides off of the momentum of his teammates, off of their dirty work, and then gloats about and rips his shirt off when he wins penalties after he dives to win them.
Personally, I'd hate to play on a team with a guy like Ronaldo. Prima donna to the T and I'd much rather have to keep up with Messi's magic or a guy like Ibra than his winy prissy ass.