Ignorant? Everybody starts out ignorant...

Riding posture preference is one of those things that change as you get more experienced. When I started out, I couldn't get upright enough. All my settings were at maximum and still my back wasn't vertical.

Now after some years I have more or less adapted to the common 45degree posture, body and arms at 45deg with the horizontal, handlebars approx same height as saddle. The forward leaning body angle allows you to develop more power from the legs due to both the upper body providing a counterweight for leg action, and the leg extensor muscles working more optimally with the body lower down. You can feel this latter effect easily by hunching down when you get to uphills - it feels much easier.