Here's the deal; if I'm going to compromise your computer and do Evul Things with it, I'm damn well going to get root access. Getting root is not that much harder to do than getting any other kind of access, and the payoff is so big (from a black hat's point of view) that you'd be daft not to do it.
This being the case, UNIX and Windows are now suddenly equivalent; they've both got IP stacks capable of opening raw sockets.
Ooh, scary! The Bad People are coming!
The only problem is that raw sockets are pretty crap as a DDOS tool when you consider what something like Slammer did; no raw socket required. And that was the most effective DDOS ever.
Steve is an excellent self-publicist. Never forget that on every visit to grc.com you, gentle web surfer, are exhorted to buy Steve's (undoubtedly excellent) software.
There are many, many security problems with Windows.
This isn't one of them.