I thought that the hardware drivers were independent of the distro? or at least debian? I lazily assumed hardware support on other distros would be crappier.
I think the big issue here is that if a piece of hardware is listed as officially supported and it still doesn't work after you try to fix it with whatever hacks are suggested, it's not a workable situation.
Technically most drivers will land-up in the main-line kernel at some point. But, for testing whether a "whole" laptop works means making sure all the drivers are working at the right version - it's fiddly. Consequently, what you really care about is whether your distribution supports that hardware version.
b. Getting support for a Linux laptop
In many ways the fact that users had to load Linux themselves in the 90's has been the biggest problem for users now.
If you want a "Linux" laptop you should buy one with Linux preloaded. That way you'll get one with a known working configuration on the hardware and software. If something doesn't work there's a venue for you to get support - the person who sold it to you. Otherwise, if you do have problems you're stuck doing whatever "the internet" tells you to do - half of which will probably be wrong, or it's just happenstance that it worked for them.
That's why buying from a Zareason, System76 or Dell (XPS 13) is important
c. Lenovo certifies but doesn't provide support for Linux
Lenovo does a type of certification for Ubuntu that means it "works for them". But, AFAIK there's no avenue to get support from them if the hardware doesn't work. Generally, it does work (writing this on one now), but you're stuck if you have problems.
I think the big issue here is that if a piece of hardware is listed as officially supported and it still doesn't work after you try to fix it with whatever hacks are suggested, it's not a workable situation.