GNU are also very hard on principals. Again, I think society started leaning quite a bit more pragmatic over the past 10 years.
In the tech industry you can see this trend for example GCC to LLVM, LibreOffice to just using Google Docs, GPL to MIT, etc.
MIT by contrast lets you do whatever you want, and that seems more like the libertarian approach to me.
It requires you share the code with your users/the people you distributed derived works to for no additional cost. You can still charge money for the software, but you can't charge an additional fee for access to the code. You also give them the right to share it how they seem fit, so they could share it (the code, not necessarily trademarked things like names or artwork/assets) for free, share derived software including the code for a free or a fee, or not share any derived work at all.
You can read more here: https://www.gnu.org/licenses/gpl-faq.html
Labeling something "socialist" or "libertarian" in a diverse place like HN probably harms more than it does good, as everyone will read it differently and have different takeways.
Socialism had plenty of that going around, sticking with older working ideas.[1][2] But I hear you.
"The Free Software Movement does not endorse Libertarianism".