That would be true if you don't have any video calls, or all the interviews are done without resume screening...
I have repeatedly had to tell recruiters that no, I am not adding a picture and date of birth to my CV.
They were completely baffled by the concept.
[1] https://www.academia.edu/35495485/The_Most_Litigious_Countri...
It is hard to hide an age :)
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.