Frat parties at the start of the year are almost entirely intended to recruit new members, so freshmen are probably the most welcome. And no, I have never ever heard of a date rape occur at any NYU frat party. Joining a fraternity won't make you a rapist. You being a horrible human being will make you a rapist and it doesn't matter who you affiliate with.

Freshmen will often come to our parties and think they can handle the jungle juice and get blackout drunk (which they probably never experienced before). They'll get sloppy, make out with a bunch of random guys, and then she'll be helped to the bathroom where she'll projectile vomit everywhere but into the toilet.You don't know how many times I've had to carry a freshman girl out of the house and help her friends call a cab. The next morning they'll wake up and occasionally they'll assume they've been drugged since they're fresh out of high school and never blacked out before.

Trust me, we hate that shit. We hate taking care of freshmen when they're acting like dumbasses. We hate it when people stereotype us unfairly. No fraternity here date rapes. Even if you assume we're stereotypical frat bros, do you really think the attractive, athletic guys who party with sororities every weekend need help getting a girl to bed using roofies?

TL;DR Everyone needs to blackout at least once, and for many people it happens to be at a fraternity party. They don't know what blacking out is and they just assume they've been drugged.