A degree is not necessary to be a 121 pilot. And being military does not make a person a better pilot than a civil-only pilot.
However, both of those things are desirable to Delta. It shows that you can commit to something, and stick to it til the end. Desirable qualities in someone that the company is about to invest (potentially) millions in. Nothing more. It’s about the person, and what they have already been thru to get to where they are now.
You are not required to like that a degree is required, nor that military have a certain advantage in getting the call to interview. But it is a fact that both are looked upon favorably by all companies.