I think ThinkPads are so commonly used because they're durable, but most of all, because their keyboards are probably one of the best among any laptops.

I can vouch for Linux in laptops, I've been running Debian+xfce (recently switched to Debian+lxde, for maybe slightly less ram usage) on my Acer Aspire One for probably more then 10 years now! It's my go-to machine whenever any hardware needs testing, be it networking or just a printer.