Having the mindset that I am happy to attend or host a loved one's 1st/2nd/3rd baby shower (party, gathering, celebration, hootenanny) does not mean I believe anyone is owed a baby shower. It means I love them, a baby is exciting news regardless of its birth order, and I love parties especially where there will be cake.
Sure, nobody really needs a party or celebration or gifts to mark any occasion in their life, but that doesn't mean those of us who want to celebrate them are doing so for nefarious gift-grabbing reasons.
Life is made up of an endless stream of shopping, working, commuting, running errands, repairing furniture torn up by cats, paying bills, forgetting the milk, filling up the car with gas, etc. It's just nice to add some parties to the mix. Babies are a great reason to celebrate, though if you want an "I went to the grocery store for the 30th time this year!!" party, I'm down with that too. I'll bring the cake.