It's because there is such a widespread perception that men have a "right" to sex and it's a basic need that they physically can't live without - like air, water, etc. This is actually used in the legal system in many countries. If you're in the UK you may remember
a case a few years ago in which a judge ruled that an autistic man who can't understand consent had a "fundamental right to sex" and should be given access to women, despite him being judged as a high risk for sex offences. (That was thankfully later overturned on appeal.) In Canada there was the
Marylene Levesque case where a prostitute was murdered by a newly released offender whose parole conditions allowed him to go to brothels for the sake of his "sexual needs."
And this is all despite the fact that statistically a high number of sex offenders are married or in relationships. They're not poor sad lonely men who can't get a girlfriend - and even if they were, they still would
not have a right to a woman's body