That’s my point. AppCleaner isn’t magic. It’s killing off some known flotsam and making, essentially, educated guesses. It occasionally gets it wrong. Less frequently with suggesting removal of something it shouldn’t have and more often by not catching “everything”.
Apple doesn’t want to be involved with guessing games and run into the potential of getting it wrong. Microsoft doesn’t do it with Windows and none of major Linux distributions that I’m familiar with do it, under default conditions, either.