On the third point, I think that of the four counter arguments, that one is the least convincing. If a candidate is applying for a new job and are asked to do a work sample or an exercise, but they can't find the time (generally exercises I've seen are between 3-5 hours long, and usually you have a week to finish them) then why are they applying for a new job? You could easily find 3-5 hours in a week to complete some exercise, even if it's broken up into multiple sessions of coding, if your goal is to work at a new company.