There’s a concept, originally from WHATWG I think, that might be worth translating for accessibility in a guidelines context: Priority of Constituencies.
The oldest reference I can find quickly is in the W3C Design principles:
User needs come before the needs of web page authors, which come before the needs of user agent implementors, which come before the needs of specification writers, which come before theoretical purity.
It could almost apply as-is, but at least for the Web Content Accessibility Guidelines (WCAG), we don’t set standards for user-agents to follow.
The nearest equivalent for WCAG would be testing, both people who test sites for accessibility and people who create tools to support that process.
So I think our version would be:
“User needs come before the needs of web page authors, which come before the needs of testers, which come before the needs of test-tool implementers, which come before the needs of specification writers, which come before theoretical purity.”
Or more succinctly: Users > authors > testers > test-tool implementers > specification writers > theoretical purity.
It isn’t all one-way, after all, it is an ecosystem. For example, making something in a guideline easier to implement for a testing-tool could make things easier for testers, then authors, and ultimately benefit users.
Still, it is a thought I wanted to get down. (Not representing the W3C or anyone else, which is why it’s on my personal blog.)