What is the purpose of this type of loop with the obscured screw?

Appears that these are MD cut loops: https://civiliangunfighter.wordpress.com/2015/12/19/dont-be-afraid-to-modify-your-gear-part-ii-magazine-carriers/

I think they're intended to be used to attach the magazine carrier to a belt....


but seriously... i think the "obscured" mounting point is to allow the carrier to be mounted lower on the belt line.  If you were to reverse them on your mag carrier, they would push the top of the mag another ~1/2 inch lower, meaning you'd have to pull it ~1/2 inch less to draw and clear the carrier.

That's my understanding of their value over traditional loops.