i really don't understand

Some sororities are even encouraged by their nationals to do spring even if they only need to take a couple girls. It's also a good way to get girls that a sorority know will be a good fit. There's nothing wrong with doing spring rush and it's not just a bottom tier thing by any means

Spring rush can be really beneficial! It's way less stressful, slower paced, and really allows you to get to know these PNM's before you bid them. A lot of the time, our spring pledges become more valuable than the fall pledges. I like being able to make a slower, more thoughtful decision about offering bids. There's no shame in that, even in old row.

A house can get some really great girls this way, the ones who didn't rush in fall or who got overlooked the first time around. Spring rush is definitely a win-win, but there are always catty girls who don't know any better trying to make it seem like a rival house is spring rushing out of desperation, but then their own chapter will do it at some point so it's stupid to use it as criticism.

I wasn't really sold on sorority life and dropped out after the 2nd round 2 years ago. I still had houses I liked but just wasn't sure. Spring comes along and a few if the houses I really liked did a spring rush. I ended up in a sorority I love, solid middle.