"Try _distro_ - everything just works for me!"
and/or
"research before you buy!"
The 'it all works for me crowd'. I don't believe most of you most of the time. "Works" is in the eye of the beholder, and most of the time I've found that people who make that claim don't have anywhere near the same work style that I do.
Example: running audio from 4 different apps simultaneously all mixed together is a no-brainer under OSX/Windows, but is something most Linux users don't even dream of, because they've never even been able to try it (whoops, amarok is running, so I can't get AIM sound alerts, etc.) If they've never done it, the "works for me crowd" can't possibly know what 'works' means for them is light years away from what 'works' means to me.
"Research before you buy". Where and how? Show me an up to date list which shows even most of the compatibility aspects of stuff I can go buy in a store against recent distros. Googling around and finding that I can get Ubuntu 5.04 running on hardware from 2004 does me absolutely 0 good. Manufacturers don't always show you the exact chipsets used (and may often change chipset revisions and just ship new windows drivers in the box), and yet even if you do happen to know every single internal spec of hardware before you buy it, no one else will have bought it to determine if it works. Someone's gotta be first, unless the manufacturers would actually start certifying that "distro X" runs on particular configurations (which ain't gonna happen).
The majority of us live in a world where when we want a computer we're going to go to a local store and buy something. If Linux users want their stuff to be more widely adopted, they need to adapt to that reality. I suspect most Linux users don't really care, and are happy being 'cutting edge' and compiling new drivers to test stuff out. Really, it's an exciting and interesting way of life for some people, but one which I and many others eventually outgrow.