I have an issue when I alt + drag elements on my screen to quickly duplicate them. If there is a locked layer above what I want to select (auto-select is on) it will duplicate the locked layer instead of the element I have selected. I use auto-select and alt+drag to make my workflow faster, and I see no real reason to be able to duplicate layers that were previously locked. Unless someone has a very good reason for doing this, I think it's a minor technical fix that would make more sense.
I heavily agree that this is how it should work. I'm having the same issue but with a layer under the layers I'm trying to alt+drag. The shapes I'm dealing with are rather small, so instead of selecting the layer I need it to select, it instead will grab the background and duplicate it instead quite often, which is very annoying.