Part of the problem is that people these days have fewer children, closer together. Before, say, 1970, people learned parenting because there were lots of both

Part of the problem is that people these days have fewer children, closer together. Before, say, 1970, people learned parenting because there were lots of both much younger siblings and large families with lots of uncles/cousins living close by. Now families are small and geographically spread out, so people don't have lots of exposure to younger children. This means they don't get as much practical experience at dealing with kids, which makes them do stupid things, listen to stupid advice, or fall into groupthink.