A bit less than a decade ago I went to "Cyber Cyling Coach", Dave Jordaan (Google) to fit my kid. First thing he asked was his FTP (hour power). Because that has a lot to do with weight on hands and also speed/aero. Also about the type of riding/events, fatigue, pedaling style etc. For junior there were different fits targeted different events. Different riding, power figured into the best fit.
As my wife and I got older (we total age over 120) our power has gone down a bit. My slammed stem was not as comfortable. I was riding slower than I used to. I was aware that lower bars were less aero when the rider had to ride on the drops with close to straight arms and that getting the forearms parallel to the ground, pointing into the wind exposed less area to push the wind.
I raised my bars - I got faster. Not a whole bunch, but some.
Recently I did a rebuild on my wife's old '93 bike (13# something). She too had had a fairly aggressive setup most her life. Her other bikes had forearm rests and she likes riding like that. I had noticed that she would rarely have her hands on the drop with bent elbows. The bars were too low. IMO they may have always been too low. Anyway for this rebuild I got the Specialized bars that rise. I raised the stack about 2 cm and flipped the step.
We are still tuning, but these higher bars eliminated the need for "aero bars". Net is it is much more comfortable, body is up a bit and speed is up a bit. The hands on the drops are just an alternative to hands on hoods with forearms pointing into the wind.
My conclusion is slammed setups with flat backs are not much needed for those averaging much under 22mph or under 300W ftp.
This is a pretty good senior citizen setup.
