The impression I get is that major Linux distros will work on almost any laptop, but if you want it to work well (good battery life, flawless suspend/resume, no issues with graphics drivers), you still need to think about your hardware.

I don't believe that Linux can ever go mainstream through just being installed on Windows machines: for most people it's just too much effort for too little reward. And for reasons both practical and principled, I want Linux to be a mainstream option. So I support people selling computers with Linux.