Maybe there's some useful info in this anecdote.

When I was fitted, they had me bend forward with a straight back and my arms hanging until I couldn't support my weight without using my arms or feet. At that balance point, my hands were supposed to just reach the top of the handlebars. I believe that a strong core allows a rider to lean over farther.

FWIW, my new frame is slightly small for me and my handlebars were about 3/4" too low with the tallest stem the LBS had. I had been riding a 30 year old road bike that is the correct size without problems. Now I have some numbness in my left hand.