The email wasn't complaining about Apple's cut of profits, but rather having their app being killed seemingly arbitrarily when Apple decided to kill a category

The email wasn't complaining about Apple's cut of profits, but rather having their app being killed seemingly arbitrarily when Apple decided to kill a category of apps from the store. Folks can have a good experience with the app store, until they don't. There's survivorship bias in creating an app unaffected by the ever changing app review policies. This isn't exclusive to Apple's walled garden either.