sophomore pnms

I am hearing through the grapevine and most of these comments have been confirmed by social media pictures that AOPI took a lot of the sophomores that rushed. I am new to this and trying to figure out why they would do this. I thought sororities wanted Freshmen because they would have them the entire 4 years. Why would one group want so many sophomores? This makes me think it is ok to rush as a sophomore and isn't as bad as people say! Could someone explain what I am missing?