He later happens onto one reason the process makes sense: uninstall just by deleting the application file. He is confused about how to install an app because there is no installation. You just put the program anywhere you want (the Applications folder thing is really just a suggestion) and double click to run. In fact, you can even run directly from the disk image, which Matt did without realizing at first that was what he had done.

So, the reason the Mac approach seems strange is because it makes the whole install/uninstall concept just go away altogether. Perhaps a suitable HN metaphor: it eliminates an onion.