He was the guy in charge, so of course they're going to concentrate on him especially considering how senior these officials were. He was either just as corrupt as the other officials to allow it to take place or completely incompetent to not notice it was happening.
That makes about as much sense as blaming POTUS when a democratic senator in the US takes bribes or kills his wife.
I mean, do you seriously think that when people take bribes, they proudly tell it around?
"Hey Sepp, old sucker! I just accepted millions of dollars in bribes for casting my vote to country XY!"
"Hey Jack! Haha, great work, high five!"
Sorry, I consider that ridiculous. At FIFA votings, about 200 people are entitled to vote. Sepp Blatter has no chance at surveiling 200 people 24/7, he's not the fucking NSA.