I’m always vaguely bothered by the statement “I don’t care who started it!” because I always imagine something like this:
Child A does something horrible to child B. Hitting, spitting, groping, setting hair on fire, verbal abuse, sabotage of schoolwork, pissing on electronics, whatever.
Child B screams, tries to defend themselves, calls for parent or guardian.
Parent: “What’s going on here!”
Child B: “Child A did horrible thing X, help me”.
Parent: "Well, I don’t care who started it, stop screaming and go to your room/back to the salt mines/fuck off. "
So, to me, “I don’t care who started it” = “The person who starts is free to do whatever they want, and the victim will be blamed equally if they make a fuss, so just take it like a good little doormat and leave me alone”.
Is it just an excuse for bad parenting? What am I missing? It’s presented as some sort of parenting mantra, something all parents identify with, and I don’t get it at all.