>>528657164
Saori unironically sees the rest of SQUAD as little kids and more often than not, she acts like their mother instead of leader.
She knows that they have codependency issues.
From the events in Vol.3 it's very clear that SQUAD with Saori as the lead is a very strong unit, but without Saori they are complete shitters.

Saori left them to figure things out by themselves with the hopes that they outgrow their trauma and stop depending so much on her.