Seriously? Have we become this b*tchy as a community of parents now, that the OP actually thinks badly of parents who deliberately let their LO get the final layer? I mean, surely everyone else got something in their layer too, so it’s nothing to get your knickers in a twist over at all.
At the parties we went to, the parents and children were all so happy for the birthday boy or girl. There are hugs and there’s clapping. No one feels the need to b*tch and moan about the parent who did that. In fact we are fond of the bday boy or girl because we know them and they are our little ones’ friends. So I don’t understand this nasty mentality. Perhaps you shouldn’t be going to parties at all if you take issue with parents making a couple of hours mainly about their child, whilst also catering for other children - that’s kind of what birthdays are for - to make a fuss? The kids get to play games after all, irrespective of who wins, they have fun with their friends, hopefully are entertained, fed, get to have some treats like cake, biscuits, sweets etc, and a party bag.
It’s really not a big deal...