The invite said small children would be bored and the parents could enjoy a child free weekend.
See, THAT'S what I find rude, not the no kids part, it's the people who say "no kids as a favour to you "
- I find it so patronising, it's also not true, couples who don't want kids do so for selfish reasons, and that's absolutely FINE! but be honest and upfront about it "look! this is what we want! it's one day and I hope you can share it with us!"
It does nobody any favours
If I had a kid who got bored at weddings (I don't! they love them!) I'ld try to make arrangements for them to not come off my own bat!
If I want "to let my hair down", I'll get a babysitter at a time that suits me and my babysitter.
etc