>EndeavourOS and CachyOS don't put any barriers upon the user, what fixes and guides that work for Arch will work for them
The Arch project itself disagrees with that, they will not provide any support or make any assurances about what works on other Arch based distros. The edges being filed of is a substantial difference, which sometimes will matter. The distros (by design) include a lot of defaults, which are assumptions Arch does not make and which it assumes users know about.
>SteamOS also clearly has a place as an immutable Arch, hard to argue that it's been a disappointment or a cause of frustration for users, given the narrative has been an overwhelming want from the gaming community for a desktop version. I guess the frustration comes from, if anything, it's narrow scope.
I specifically talked about managing Arch yourself. On the Steamdeck you never have to touch a console to make things work. Valve will provide updates for you, no manual intervention needed. It is also well defined and extensively tested hardware, which does not apply to anything else. No user should use SteamOS outside of the Steamdeck, Valve is clear about that.
Besides my main point still stands. If you can not install Arch, you lack basic Linux literacy. The moment your Arch based distro based, you can not fix it without these basic skills. You will be disappointed and frustrated and unless you are willing to spend a lot of time learning (after which you could just install Arch anyways) you will never touch Linux again.