Much of that technology looks old, but isn't: ropes have been around a while, but modern climbing ropes stretch so as to drastically lower the peak forces on your protection. For example. Modern climbing exists in large part because we developed technology that lets you try to climb hard high stuff without dying.
Now, you could also get good just by bouldering, staying close to the ground. But that's not how actual existing climbing developed: bouldering grew out of crag climbing, which grew out of mountaineering. It's a little silly to wonder why people weren't very good at a game we just invented, before we invented it.
Another point. We don't actually know how good the best climbers were throughout history. There's a clear upward trajectory to 19th-century British mountaineering and its descendants. But how good were the best Incan climbers in 1350?