After all it serves no purpose, requires development of new tech, money etc..
I don't think anyone doubts they couldn't have done it long ago were some local ruler to have made it a priority.
I wonder if they thought the original European 'explorers' to be completely mad.
So that leaves the question: the mountains were 'right there' and they had innate ability, so why didn't they 'just do it', and have the routes all mapped out for centuries already? Is I think the rhetorical question that unpacks a lot of things.