I kinda agree with you, but when you see 21% at Rackspace, it shows that something odd is going on there (taking out hosting-specific attacks, the % should be the same everywhere).
Heh! I just added a link to your blog as a recommendation, before seeing your reply.
My guess is that more of the stuff at Rackspace is being admin'd by customers who don't know what they're doing, versus the managed shared hosting at other places.
