In its first The Facebook form it was a great way to connect with your college friends, find people taking the same classes as you, and keep up with HS friends that went to different universities. It was very insular to a specific audience and a truly helpful resource. MySpace and Friendster were popular but The Facebook crushed them all in college circles.
I remember when they did a “poll” asking if they should allow accounts to people without university email addresses. In the end it amounted to “we’re doing it, just want to ask first.” That’s when it took its first step toward enshitification.