You should read my reply to the other guy for a fuller treatment, but here's what I said about this to him, 'perhaps "demand" was hyperbole, but CSS does still push developers to rewrite their HTML when design changes happen.' The cost in flexibility to do it any other way is simply too high. This is sufficiently close to demanding to justify the hyperbole, in my mind.

edit: Furthermore, you speak as if the author is criticizing floats, but he is not. He is criticizing the attitude that tables are to be avoided for layout at all costs, when there simply is not a simple, implemented, cross browser way to replace them. Floats are simple the closest thing we can practically use, so he uses them for comparison.