While this may be true for you, it does not apply to everyone.

I used the drop bar setup on my 520 for about 1000 miles. It was OK, but not very comfortable after 30 miles into a ride. And the handlebars were as high as the saddle, had two layers of cork tape, etc.

Then I thought I'd try matching the setup I have on my MTB/commuter.

Worked even better. But still a little bit short of perfect. I then altered the barends by putting dual/density MTB grips over the barends and tweaking the angle a little.

Perfect (for me). Usually when I ride I experience a little tingling/numbness in my hands for the first few miles, then it goes away, then returns after 30-40 miles. If it's a long ride (75-100 miles) I may experience numbness in one or two fingers for several hours after the ride.

Over the weekend I did about 7 hours of riding. No hand discomfort at any time. Plus I prefer the position of the brake and shifting levers on a flat bar. I find that I have a variety of hand positions on the flat bar with barends.

I think the key is to find out what works for you and your goals. My selection of cranks, handlebars, shifters and brakes were all made after using the original setup and comparing it to what worked for me on other bikes I have used.

Plus the original poster did not ask our opinion on his/her choice of handlebars.