Why might avoiding responsibility through projection have been important for staying in the group back in the day?

Is there a reason why projecting our own flaws onto others might have been helpful for our ancestors' survival and social life?
Is it a coincidence that so many social media influencers are good-looking women in their 20s to early 30s?
What are some common mistakes people make when trying to confront strong personalities, and how can I avoid them?