I think this is maybe a reaction to the way AT&T made Unix so expensive and inaccessible to hackers for so long that the idea of charging $$$ for something whose marginal cost of production was effectively $0 that the idea of charging money was morally repulsive to a lot of key figures in the movement.
In a way OSS seems like the sort of thing that would have worked great in some hypothetical enlightened communist system that didn't suppress liberty.
> AT&T made Unix so expensive and inaccessible to hacker
Actually you got it wrong, it was precisely because AT&T could not legally charge the prices other vendors were selling their OSes, that UNIX got adopted by universities and small business, thus spreading its use in the industry.
The ones charging lots of money for UNIX clones were Sun, HP, Digital, HP, ...
I thought sun was in partnership with AT&T when system V came out, and https://en.wikipedia.org/wiki/History_of_Unix appears to support that idea, but my first-hand memories have dimmed with time (cause it's not something I care about that much) and you may well be right.
I do remember, um, liberating an overlooked copy of system V/386 on 5.25" floppies that I found in a storage cupboard when I worked at PC Magazine in 1992 :-)
"Unix came into many CS departments largely because it was the only powerful interactive system that could run on the sort of hardware (PDP-11s) that universities could afford in the mid '70s. In addition, Unix itself was also very inexpensive. Since source code was provided, it was a system that could be shaped to the requirements of a particular installation."
Sure, marginal cost is $0, I agree. But building and maintaning huge swathes of million (billion?) dollar infrastructures/architectures for enterprises for free feels somehow more wrong than building a small business that supports a few maintainers' families.
In a way OSS seems like the sort of thing that would have worked great in some hypothetical enlightened communist system that didn't suppress liberty.