"Steve Stone" wrote in message
...

As FM became viable in the very
late 60's and early 70's, ...........

By viable do you mean profitable ?

That is what "viable" in a business means. Very, very few FMs made money
from the first ones pre-W.W. II through the very late 60's. In fact, from
1950 to 1960, total FM count declined by nearly a third.