Why do some civs lack Heavy Cavalry Archers?

I was wondering this, and I felt like reading your opinions. Some civs (Teutons, Vikings, Malay, Portuguese, Italians) lack Heavy Cavalry Archer, but their lack of upgrades for them would make teching into HCA useless anyway. I could still kind of understand the portuguese one since their gold discount could be useful there or something, but still. So why do you think those specific civs lack the upgrade?