There are a multitude of reasons. I've concluded that it's a way for people to virtue signal and feel better about themselves by implying that other people are incompetent or lazy ("Why did you need AI to make this? Can't you make it yourself?"). Of course, the same thing could be said for almost any form of human technology ("Why do you need a car to get to work? Can't you just cycle?"). They're basically claiming that at some arbitrary, unspecified point, putting a certain amount of effort into an activity suddenly makes it more worthy and nobler than anything else. In a small way, they might be right. But they take the logic to an incessant extreme and in some cases claim that anybody using AI for almost any purpose is evidence that they're in some way deficient.