You are absolutely correct, they sharing culture was
around throughout the
50s and 60s. In fact the IBM "DECUS" equivalent was (is) called Share.
When I say, dop really was creating the idea of FOSS, it was different
from the sharing that had occurred previously.
I had an interesting experience with "open source" in the 1960's. My
first published paper, called "Hierarchical Clustering Schemes", described
a way of taking non-dimensional data (e.g., "A is more like B than it is
like C") and finding clusters of objects that behave similarly. I had
written a modest-sized FORTRAN program to carry out the algorithm--it was,
as I recall, between 100 and 200 lines long. As a postscript to the
paper, readers were invited to write to Bell Labs and a card deck of the
program would we sent at no cost. We expected a couple of dozen requests,
but in fact sent out, as I recall, nearly 500 card decks. A couple of
years later I started getting reprints of articles that referenced my
paper, the authors' having analyzed their data with the program. Many of
the papers were unusual, to say the least (in one, the program was used to
do organize the Latin curriculum in Poland, for example...). The paper
had over 700 citation, and, the last time I looked, was still my most
cited publication.
Ah, the good old days, when people who used free software actually
acknowledged the original author(s)...