I understand why (tying to avoid the "yet another Linux distro" stigma), but when you go to "What is Qubes OS?" in https://www.qubes-os.org/intro/ ; they fail to mention that is Linux based.
Well, to be fair this one has a FAQ entry: https://www.qubes-os.org/doc/user-faq/#is-qubes-just-another... ; although they try to understate that they use Linux.
If they want me to trust them, they're doing it wrong.
buy they don't. They want you to look at their hands. This is a security oriented distribution.