If hiring managers really want to hire based on skill, what they should be doing is testing for one thing:

The ability to take a specification, written in general language, notice deficiency, communicate with the 'client' (manager) to hash out what needs done, and the (explicit) ability to read documentation on libraries or tooling outside the dev's core skillset.

If a dev can read a spec, talk to a client to work out whats lacking, and then identify what they need to know and where to find it, thats 90% of the skills they need from what I can see.

tl;dr version of it, is they should be explicit about the requirements for reading/implementing specs and finding the correct documentation.
Something along the lines of
"can you form your letters? Are you able to follow instructions on the back of a cake box? Then there may be a position waiting for you!"