there are thos who see the purpose of sex as necessarily procreative. According to procreationism (as it is sometimes called), any sexual activity that is inherently non-procreative, as sex with a robot must be, violates this natural purpose of sex, and is therefore immoral. . . . Such people do not generally insist that each individual sex act must be intended to produce children. Rather, they argue that acceptable sex acts must belong to the class of acts that could potentially be reproductive.
Neil McArthur, "The Case for Sexbots" in John Danaher & Neil McArthur, eds., Robot Sex: Social and Ethical Implications (Cambridge, MA: MIT Press, 2017), p. 35