There’s a saying about how one should consider when you’re pointing the finger of blame, there are 3 fingers pointing back at you. While some of the sayings may make sense in their original context, such as the ones about resentment and grudges and have to be twisted & manipulated to be used against people, this one doesn’t even make any freakin’ sense.
Sometimes people deserve blame. Such as when they’ve done something wrong. When I hold family members accountable for their emotional abuse of me, I don’t have 3 fingers pointing back at me. And to suggest so is to evade responsibility and accountability for one’s own actions. And it adds insult to injury, because under the guise of being more enlightened, the speaker of this pithy platitude is trying to shift accountability/responsibility to the wronged party. Implying that the person calling for accountability is morally flawed to expect any sort of accountability.