Condensed milk was a positive change, though, in the early 20th century.
Babies who were not breastfed had cows milk, which was not stored properly in houses or shops, and was brought in milk churns on the milkman's cart, pulled by a horse.
In the summer, especially, it quickly went off.
Condensed (and also evaporated) milk was canned at the factory and had an indefinite shelf life. This undoubtedly saved many non-breastfed babies' lives.
Nutritionally, obviously, it was a great deal poorer than breastmilk, but hygeinically it was a whole lot better than bacteria-ridden ordinary milk laced with horse shit
I think this is what lies at the heart of the folk memory, certainly alive in the 1970s according to Gabrielle Palmer, that condensed milk was 'good' for babies.