A helicopter will crash if you just look at it wrong. I'm not quite sure why this is surprising to a lot of people.
Just because a helicopter can go faster than a drone, doesn't mean it's always going faster than a drone. The benefit of vertical take off is that you can land and pick up troops in dangerous areas.
More than likely this is the same scenario as whenever they shoot down one of ours with an RPG in Afghanistan. Got them right after touch down or take off, or got a lucky hit while they were flying low and slow.
Mongolians are mainly known for their horsemanship rather than their marksmanship. They are probably the best marksman on horseback that have ever lived, but as far as historically being known for their archery.....that's the Koreans, and they're still pretty dominant in the Olympics.