For instance, the whole you can't give advice thing because you don't have kids. Yeah, a kid less person probably shouldn't criticize my parenting... it is a difficult thing to "walk a mile" in. And every kid is different, mine are night and day personality wise, so it is impossible to say "You absolutely needed to do this." However general advice...
MVP I was really surprised to hear you didn't have children. Not only was your advice spot on, it was spot on development wise as well. Do you work with children? I have kid free friends who try to help me with advice (god how many have googled DS1's sleep problems!) and they ask everyone with kids they know. They listen to me, and that's the most important part.
They have plenty of situations in their life which haven't happened to me and won't. I give them advice on those... not that different. I don't get the defensive behavior.
I do think those who are vehemently anti kid do need to remember... most parents are doing the very best they can at that moment. Not trying to inconvenience them or annoy them, but some kids are tough and some situation are hard to fix right away. There needs to be more understanding on either side, just because we chose different paths doesn't mean we need to be against each other.