So many valid points littered across the thread. Couldn't have explained it any better myself.
This thread had a great start with
@Jesse Pinkman 's initial observations. They were very relatable. Even though I attended college from 2001-2005, a lot of what he discussed initially was relatable to my experiences on campus in that era.
Two of the biggest differences between being on campus 2001-2005 and being on campus 2013-present would be swipe apps and social media. When I was on campus, online dating websites existed but were rarely used in the college community in those days. In the 2001-2005, dating websites were used by the post-college crowd and were still somewhat stigmatized but did de-stigmatize a lot during those years. To a college student in 2001-2005, dating websites were something "older people" did. Many of the college students of 2001-2005 used dating websites and swipe apps later in life. Tinder launched in 2012 and early Tinder became popular on college campuses in its early days.
Since 2013, it would be possible to go through 4 years of college and not have to do any in-person approaches. It would be possible to rely on swipe apps and Instagram DMs to arrange dates. In 2001-2005, there was a need to do some sort of in-person approaches to get dates. A non-Greek Life male student in those days could do random on campus approaches, approaches at extracurricular activity events, approaches at off campus parties, and approaches before/after classes of women in those classes. Since 2013, I would guess all those forms of approaching have declined.
Facebook launched in my junior year of college and it was rolling out in my senior year of college at my university. By senior year, I had already gotten on MySpace. MySpace and Facebook in 2004-2005 were a less a part of college students' lives than Instagram later became 2013-present.
Even cell phones were different in 2001-2005. In my first 2 years of college (2001-2003), many students still didn't even have them. For the ones that had them, the phones were very basic and only used for calls while out and about. Precursor to text messaging, such as AOL Instant Messenger and Yahoo Messenger on computers, were popular among college students then. By my last 2 years of college, basic phones had gotten more popular and there was some small amount of texting, though texting on basic phones was more difficult.
The tech changes have affected college sex life a lot since I graduated.
Additionally, gender ratios have gotten more feminine. When I arrived on campus in 2001, my university was near a 50-50 male-female split. I recall evaluating the ratios at the schools I got accepted to and all of them were close to 50-50 at the time. Now, college campuses are closer to 60% female. Even with more females than males on campus, a good portion of males on campus are sexless as females only pay attention to the top tier men.
At my university, even in 2001-2005, a good portion of men were invisible to a lot of women.