I forgot how snobish cyclists are.
Many years & lbs ago when I had the time for 3-4 hr rides I too laughed at the weekend warriors with the expensive bikes and desk job guts crammed into their team replica jerseys. I would drop them on my mountain bike. Now I'm one of those guys I used to laugh at (minus the expensive gear).
Ride whatever gets you out the door and on the street.
Edit - dang forgot to address the main question. Senior moment... Yes. Steel frames are sweet! If you're buying second hand I'd stay away from carbon. Have the frame and components checked out for possible stress fractures before you pound on the pedals or bomb the downhill.