Yes, it's a little counterintuitive, especially after so many years of using Corel. I expect to mask something, make it into an object, and then be able to stick stuff behind it.

You seem to arrive at the same point with layer masks, but so far, it feels a little clunky. I'm sure it will eventually make more sense, but anyway, I must have learned a lot for my poor little brain last night, because I had layer mask related dreams!