I don't think this is true at all. In 1989, I bought my first serious road bike. It was a Miyata 912 and it came standard with a complete Shimano 600 group (including the hubs!), Nitto stem/bars/seatpost, Wolber rims, a Selle Italia Turbo saddle and Panaracer tires. The frame was brazed/lugged, triple butted and splined Ishiwata. Everything about that bike was extremely high quality and had bulletproof reliability. Even the paint was nice. For that bike I paid $799 (full retail), which is about $1,700 today. I challenge anyone to go into a bike shop and get similar quality today for $1,700.
You may argue about "performance" of a steel seven speed relative to "performance" of a modern carbon bike with 11 cogs, but that's both debatable and hardly fair. A better comparison is did you get a better deal on the spectrum of performance available at that time. Regardless, I'd still take that Miyata over any $1,700 bike today.