Imagine you have a job, let's say, as an in-person customer service representative. You have peers, who have the same duties as you, just different shifts or windows. And you have a manager, your supervisor. Think about how peer reviews would effect the environment as opposed to standard evaluations from supervisor and occasional reviews from clients.

I never understood why people want to hate each other so much. We are a community, and staff are supposed to be it's best members. Yet, there is already so much hatred within staff that peer reviews can only bring it to the next level. We should all be friends, respect each other, help each other if any issues arise.

Leave reviews to usergroup leaders, they probably know more than your peers how usergroup should work, and what is considered healthy workflow. Even if they stick to a conservative policy of dealing with inactive or otherwise underperforming group members, that is fine. Most staff members are chosen carefully, and everyone has their ups and downs, so there are only a few cases that require immediate actions, which are obvious without peer reviews. As part of the usergroup, you need to support your peers by offering them help, cheer them up, and be respectful to their irl issues. Instead, some people running to higher-ups with their tongues out saying this guy did this that guys did that and the third guy disappeared. And peer reviews essentially encourage the latter behaviour.