True but one quite tightly linked to particular software (OSs). And that is the problem. A little bit like early days desktop linux - there was always some or other peripheral not supported.

There is jailbreaking, CM etc and Ubuntu & Sailfish can be installed on other HW but often there are show-stoppers. In that sense, you are wrong.

I want a recognisably Linux phone implementation, like Maemo (never used Meego/Harmatten), open and working flawlessly on modern hardware. HW keyboard would be a plus but I am resigned on that account and pocket bluetooth keyboards do the job.
Sailfish is a contender. I hope Ubuntu Touch is too.