Did you forget dialup was a thing? No one created anything for home users thinking it would be behind some firewall because as said Windows didn't ship with one, and because the dominant way of customers getting online was dialup, giving a public IP to every user.
Software was created with no security because no one demanded it because no one cared. Technologies that came later did not create that situation.
Software was created with no security because no one demanded it because no one cared. Technologies that came later did not create that situation.