People that send invitations get to set some terms, people who receive invitations get to decide whether they want to accept those terms and come. All the points you made are from the perspective of a guest at a wedding, most of the stuff he posted is from the perspective of someone planning a wedding. These are two different parties, their interests may not always align perfectly. If you are butthurt enough not to show only because you are not allowed to bring your kids, then the terms of the invitation were an excellent filter.