Yeah, everyone has different needs, but very few of my clients still use dial-up modems. In fact, many new laptops (and netbooks) no longer have them built in.
So while I'd agree that if u need dial-up, and you're not prepared to do some manual labour, Linux may not be the best way to go, I'd still say if you're an average Netbook user, who needs email, web access (via wifi and/or 3g) and to type a document now and then, any of the options in the article would be fine.
I definitely think it's inaccurate to say things like "none of the Linux operating systems can handle a modem of any kind" and imply that portability goes out the window.
(Incidentally, you don't wanna know how many problems I've had installing dial-up modems on various flavours of Windows over the last 12 years or so. It doesn't always just work, believe me. I'm just glad dial-up's almost dead.)