The way one recruiter explained it to me is "they want to build a mental image of the candidate while looking at the CV". So either (a) they want to discrimin

The way one recruiter explained it to me is "they want to build a mental image of the candidate while looking at the CV". So either (a) they want to discriminate (even subconsciously, like thinking 'I can't imagine this face having this experience) or (b) (which I find more likely) they just want to turn away candidates before investing the 30-45min first call that's meant to establish that the CV and the person actually go together (and the candidate hasn't just made wild shit up). So "understandable" but undefendable in my eyes.