It's totally for the manager, they gotta fill their calendars to look like they're doing stuff. I hate when they want me to rank myself from 1-5 on various things just to tell me, "I don't think you're a 5, you're performing as expected. COL raise." I just put 3's on everything and wait for it to be over. Our company (whose application I built from scratch) just started doing this with a new manager after 6 years and I put in my notice on the first one.
My buddy put's all 1s. It's a stupid business culture bullshit thing like mandatory after hours "team building" exercises and stupid infantilization things they love to do now. The best managers on the best teams I worked with never did this.