I truly wasn't being pedantic. Pretty much every project I've worked on has required me to learn some new layer of technology that I never even knew existed. Sometimes it's just too much for one person and you have to rely on the strengths your team as a whole. The idea that a single developer can rapidly learn all of the layers/technologies affecting his/her project is a fallacy at best.

[Edit: However, in the spirit of the OP it's perfectly reasonable to expect your devs to know or be able to learn SQL.]