I bought a 1986 steel-frame Panasonic touring frame off of e-bay 18 months ago and built it up with mostly new parts.
I’ve since put 4000 miles on it commuting to work.
Rivendell’s are nice, but they are crazy expensive (of course, this seems not to be an issue for most piggs) and I’d worry I might chip the paint.
My other bike is a 1982 Colnago (steel lugged) piece of beauty with probably 15,000 miles on it.
Rust? Pushaw. You could leave it in the rain every night until your new mortgage is paid off and it won’t rust enough to lose structural integrity. Today’s aluminum frames won’t be on e-bay in 20 years.