They can certainly protect against this but it's not a good idea.

I pay US taxes and I don't want the cia.gov site to be on the same type of hardware as say Google just to be DDoS "proof".

They shouldn't be connected with a 33.6 modem but to ask all sites to upgrade everything to prevent DDoS is insane.

Who could afford to start a web site if they had to lay out all of that cost?