I'm talking specifically about native, non-professional apps targeted at regular consumers (such as grandma, aunt Suzie, little Billy working on his science pro

I'm talking specifically about native, non-professional apps targeted at regular consumers (such as grandma, aunt Suzie, little Billy working on his science project). These are the kinds of apps that are published on the Mac App Store. Apple specifically includes Performance as a section under its App Store review guidelines. I bet if you submit an app that gobbles up more than 8GB of RAM and starts swapping like crazy on a baseline Mac, you'll get rejected by the review team.