I'm guessing they don't want to officially support any specific distro, and offering support for multiple distros is probably a bit outside their wheelhouse at the moment. [e: this is perhaps not the case]
> Officially supported
> Fedora 37
> Ubuntu 22.04 LTS
https://frame.work/blog/framework-laptop-13-with-13th-gen-in...
Optimized for Linux
We continue to focus on solid Linux support, and we’re happy to share that Fedora 38 and Ubuntu 22.04 will work fantastically out of the box for both the 13th Gen Intel® Core™ and AMD Ryzen™ 7040 Series models. We have thorough setup and troubleshooting guides and will continue to provide official support for these two distributions. Manjaro XFCE 22.0 and Linux Mint 21.1 are also working great, and we’re detailing the documentation for those as well. You can check compatibility with popular distros as we continue to test them on our Linux page or in the Framework Community.
I might find myself ordering one of these.
Not shipping with Linux installed gets Framework out of the business of managing distros and images themselves. They also dodge a neverending barrage of "But what about my favorite distro X?" that would surely come for them as soon as they picked some fixed set of distros.
If you are uncomfortable assembling computer components and installing an OS yourself then linux is probably not for you. This acts as a filter for people who are serious.
It's a lot easier to support newbie computer users on windows, and they are a lot more likely to get support from friends and family.
They would be shipping a DIY edition anyways, this vastly simplifies their inventory.
These may offend your Linux-maximalist sensibilities, c'est la vie.
Personally, I kind of wish System76 would sell framework laptops with a generalized configuration and PopOS pre-insalled.
Including any linux distro would be better, because it would show a growing linux desktop market share.