David Cone did it with 88.
But still, 99 is (obviously) an average of only 11 per inning. That is impressive. By definition, a perfect game will have a lower than usual pitch count, because there's never a ball four, and starting over with a new batter, likewise with a hit, error, etc.
Yeah, the pitcher throws a perfect game, but the defense has to make all the plays cleanly. I suspect, however, that more almost perfect game efforts are spoiled by batters reaching base some other way. To be more precise, I would expect that an error ending a perfect game occurs less than any other "spoiler" event taken individually.