The difference between today's steel alloys and the stuff up through the eighties and early nineties is pretty big. Not to say the older steel wasn't great. My SLX Tommaso is still a joy to ride.
But the air hardening steel alloys of today are pretty damn amazing. Light, strong and responsive. One local frame builder I worked for never used the traditional brace between the chain stays at the BB shell. Consumers and LBS people complained occasionally, thinking he left it off due to laziness. Not.a.chance.
In the old days, a steel rear triangle was kinda fragile. Re-spacing dropouts was done with ease. Cannondale bragged how strong their rear triangles were by showing a rider crouched on the rear dropouts of a bare frame lying on the ground and said, "If you did this to a steel frame, it would collapse!" or something to that effect. And they were right.
Well, that ain't the case today! Or at least with the steel frames I was tasked with working on. The True Temper rear triangles were BEASTS! I often had to re-space cross frames from 130mm to 135. So that's just 2.5mm change at each dropout. Well, it took ALL my 200 lbs and strength to get these things to budge. And this was with all the right tools, frame table, etc. And again, no chain stay bridge. And this was the thinner stayed road/cross frame model. The mountain frame chain stays were even beefier. Luckily, I never had to change spacing on them; doing so would have required a press. So today's steels are in a completely different arena. There's really no comparison to the previous chrome molybdenum steels of yesteryear.
Problem is, the industry has (or says it has) "moved on" to bigger and better things. Progress, technology, carbon fiber is "space-age" stuff, blah, blah, blah. Steel lost its sex appeal decades ago (for the average, less-knowledgeable consumer). Those of us who know quality bikes & frames still have a great appreciation of quality steel frames. And luckily for us, they're still widely available, if mostly at the boutique level. That said, it's nice to see the big manufacturers like Surly, AllCity, etc. keep the consumer steel market going. Even the big manufacturers have resumed steel production after abandoning it over a decade ago.
Steel is still real, but you won't find it adorning many full-page ads in the latest cycling rag.