I've learned FTP doesn't mean a lot in the general scheme of things...performance riding, Zwift racing, etc.
I'm 66, 5'4", 147lbs...my Zwift FTP is 216 and my max heart rate in a Zwift race this winter was 182.
I've done well in the ZRL/WTRL racing and TTT leagues often beating out riders with much higher FTP.
Fitness and ability depends on a lot of different factors...I climb well but on the flats against larger riders/higher FTP's I have to work harder...typical in such a circumstance but I also TT quite well and that balances out my size/FTP against a bigger rider. While not a great sprinter I can beat others with higher FTP's as well...placing, knowing when to go, etc. as well as a high pain threshold also play a big role. But overall larger, stronger? riders will beat me in a flat out sprint.
It also depends on training. You have to work hard to achieve higher levels of ability with lower levels of exertion...as Greg Lemond says "it hurts just as much but you go faster" which can also mean at a lower level of effort it is easier because of your training. But if you don't push yourself with regularity to achieve higher levels your abilities are diminished and while you may be able to achieve a high w/kg or watts it is generally for a very brief period of time and recovery takes longer thus you lose ground in an event.

While age is a limiting factor, training and determination play a very big role in abilities.
You can stage the situation for numbers...as you state in your comment "The final result was 248 watts averaged for 20.5 miles. I chose a 2% grade and regulated the resistance to keep cadence between 70-80 for the most part." A controlled example compared to say a race where near max efforts for brief periods repeatedly may sap your strength and endurance because your body/mind have not prepared for that type of exertion...compare an ultra distance rider/TT specialist to a track sprinter as an extreme example.
Lastly it depends on what you are trying to achieve. Training to be more fit, strong and efficient is wonderful at any age but at the "seniors" level it is truly wonderful when you compare yourself to others in your generation. I also believe that the increased physical fitness also crosses over the mental fitness...you are improving/increasing your body chemistry meaning you also have to train your mental processes to stay focused on the task which improves/increases mental fitness.