Can anyone tell me what the purpose of having the under-sink face plate mounted with a top hinge is?

We just moved into our new to us (built 1979) house , and can't figure out why the hinge mounts from the top of the under-sink face plate so the face plate swings up, instead of down. I've seen these normally mounted from the bottom hinge and a small tray on the inside, but don't know what purpose this serves to mount with a top hinge?