Once you add both hands to the equation, there's a lot more to it than simple "dominant hand on top." I write and throw right handed. Those both involve just one hand. However, I shovel, broom, vacuum, and play pool left handed. I screw off jar lids with my left hand. I wield a cane left handed I shoot with a righty stick. For all of those reasons, I think this makes perfect sense for me. I hold my left hand on top with all of those things and it feels good to me.
When I'm in net, I catch left, therefore having to stickhandle left, (which is no good for me) but after playing baseball for six years, I just don't think I could ever catch right in net. After all, when you look at numbers, almost all goalies catch left at pretty much every level of hockey. Those numbers match up very well with handedness.
Unlike a lot of Americans, I picked up a hockey stick well before a baseball bat, so that explanation is out for me. In fact, I'm pretty sure I picked up a shovel before any of that junk.