It's all part of a general normalisation of the practices and behaviours depicted in pornography, isn't it? Like, oral sex used to not be all that common, and even when it became so, people used to ask "spit or swallow?". Spit or swallow? How old-fashioned. Pubic hair? Eugh, gross. Then you have teenage boys thinking that anal sex is something that all women should be willing to participate in, and everyone expects ejaculation on a woman's face as a usual thing. I'm a sex-positive person, and I don't really go in for feminist arguments against pornography all that much, but these things seem worth considering.