I bought one (an Oryx) to replace a macbook because it comes all set up and ready to go (no driver problems, no tinkering needed). I know it would have been cheaper to buy a machine and install linux on it but its a lot of extra work. I'd honestly just rather pay them to deal with it.
I'm using there OS (pop!) which is Ubuntu based, and works fine (although I'm not sure why they have there own OS, it gave me pause frankly, they have Ubuntu as well). It works well and seems to have updates quite frequently.
I really like the machine, its had no problems and has been easy to setup and use. There are some minor things I don't love, the battery life isn't great and I have to reboot to switch video cards (the laptop has 2 and only one supports external screens).
But jetbrains software works and the web works fine, so I'm pretty happy.
I think this makes sense. Their core bussiness is producing an integrated Linux hardware/software package. When a compatability issue comes up, they probably don't want to have to wait on a third party to resolve it; especially when they can still leverage most of the work that said third party does (and; I presume, contribute back their work).
It's a matter of branding. Which is great too as long as they keep up to date with security updates and such.
The only issue I have with Pop is the name... and I guess that's something I can get over given how well it works. :)
The fans run a lot, (especially when using the Nvidia graphics). I tend to push the machine a little though.