It may be prima facie, but it's also completely subjective. There are a plethora of reasons a person might not complete a degree that have nothing to do with his ability to commit, complete long term goals, or anything else. Using a degree in such a manner is an indicator to me that the person doing it is either incapable of engaging in critical thinking, or else is too lazy or indifferent to do so on this matter. In that regard, a person using such a filter is itself a (negative) filter, for me, with regard to whether I want to work with them.
I agree. I'm just repeating, and adding a little commentary to what I get told whenever I ask why any particular position requires a degree.
Want to be a tech writer? Samples aren't good enough. Gotta have a degree - any degree. But you have to have a degree.
So who ever made that rule had a reason at the time: expediency, prejudice, ignorance. But it's a widespread practice, and describing it does equate with condoning it.