[1] Free Software originated with GNU which was started by Richard Stallman, an American at MIT. Open Source originated in Palo Alto, CA as an alternative (less political, more business friendly) approach to Free Software. There was freely available software prior to the formalization of terminology and licenses from organizations like FSF and OSI, but even then most of it was from developers in the U.S.
[2] Prior to the Internet, most open source projects were heavily concentrated in the U.S. as large scale distributed projects weren't a thing until the 90's with widespread availability of Internet access.
both sides of this odd couple had different motivations and restrictions, but they cooperated in building the network and the software that ran the network. People here have complained, but I claim, TCP/IP was not the only network game in town then, and the massive scaling that you see today was not done yet, and did not work for lots of reasons. Many OSS projects related to the network itself, the signals across the network, and math/science. The media world was largely influenced by commercial print and Hollywood, and was less influential in the early days, as they stuck to the commercial distribution mechanisms. Network media tended to be odd, music-oriented, or sick things, in those early days. Also note that single, massive source code repos were not a thing, so people traded "tarballs" with important releases of whatever.
Which, by the way, took 8 years... typical length for European's who really don't feel like graduating (back in the day).
It's a bit out there, but I do believe there is some truth to op's points.
But open source projects still need a roadmap, focus and maintenance, regardless of how they are funded.
If you just want to share code, that's fine as well, but that's not an OSS project (sure, it can be an open source "project" - but not a project that grows)
Why is sharing code (as long as an OSS license is attached) not open source?
Under what circumstances am I allowed to call things I do open source, under what circumstances not?
outside of a few specific areas; like compilers but that's mainly because hardware is constantly evolving.
Contrast that to FOSDEM, which is completely different. This isn't just an offspring of early hacker culture. This is as offspring of how "socialist" european university systems were.
A lot of bigger OSS projects were started during peoples university time and what's so fundamentally different between how universities in Europe were before? You didn't have care about graduating. Some people stayed in University for 10 years, it was free and sometimes even had some benefits, like cheaper healthcare.
Now studying forever subsidized isn't always a good thing, but it has some nice side effects, like being able to work on your side project without having to worry about your livelihood(something that is unthinkable in the US).
The European higher ed systems has gotten more and more close to the US system with the Bologna process[1].
Most Americans immediately think about how to monetize things, and don't get me wrong, being able to live off of your open source project is nice, but it wasn't the focus in the past.
[1] https://en.wikipedia.org/wiki/Bologna_Process