I thought it was basic etiquette to mute your mic if loud obnoxious noises are incoming from your end. Did that change?

If your baby/kid is crying, apologise and go see what the deal is. Sure they scream bloody murder for the sake of screaming, but assuming they're just doing it for attention again isn't the best route. Many a sad tale comes out of parents assuming the kids calling wolf again, when yeah.... nope - something is genuinely wrong.

That's not even a judgement of one's parenting, that's just a 'brah' moment.

I personally think anyone who allows their kid to screech in the mic and makes zero attempt to remedy the situation is pretty obnoxious.