Most mass produced lugged steel frames from Europe up to the 80s were pretty crap. I currently have a Fuji and Raleigh both made in the early 80s and the Raleigh looks like it was made by school children. I have also had older French bikes and seen Italian bikes that very much agree with this.
Furthermore, a study was conducted by Keith Bontrager at UCSC that indicated that TIG welding resulted in a stronger steel frame than brazing. The durability of old frames compared to new frames, in my experience, reflects this.