I don't think you can lump 'my child, my rules' with 'my house/ wedding my rules' etc...
I have pulled the 'my child, my rules' out for mil when all other discussion failed. It was nothing to do with manners.
I was requesting that my pre-schoolers who can't swim did need an adult in the pool with them, especially given it was over their heads.
Mil insisted they were safe and could 'hang onto the side'.
DH and I weren't there, before anyone asks why we weren't in the pool too.
Tbh I don't think parenting is 'decision by committee'. Of course there many influences in a childs life, and advice should be offered/received, opinions respected and experiences shared between wider family and friends. But at the end of the day, parents or caregivers make the decisions about their children.
It's not a free-for-all, nor should it be. So IMO, in the right situation 'my child, my rules' is absolutely fine.
Incidentally, where I live it's considered bad manners not to take your shoes off when going into someone else's house. I twigged eventually after committing many a faux pas.