"But no, in both the worlds of programming and operating systems, there already were better thought-out solutions."
There were differently thought-out solutions, but not necessarily better or worse. Perhaps the issues they thought out didn't matter as much at the time and very unlikely to matter even a little bit today, and who knows how much they got wrong and much worse. It's very hard to speculate. But one thing I'm sure of is that these things cannot be really well designed from scratch and all the problems manifest only once they are used by people. So widely used systems can only be compared to widely used systems, not something niche or unused.
Sure, but we're not talking about niche systems. There was a whole flourishing world of computing before Unix and C came to be. In fact, a lot of significant theoretical and practical advancements came from that age.
Our industry does seem to be stuck in circles, continuously forgetting the ideas of past cycles and reinventing them, only for them to be forgotten again. To see that phenomenon in action, one does not have to look much further than the last 10-15 years of history of JavaScript to see how the web ecosystem basically slowly reinvented already long established practices from desktop operating systems and GUI toolkits...
I don't think that's a fair characterisation of Javascript development. It's more that people gradually realised they want to do more and more. But when they've finally understood what they want to do, they quickly adopt learning from elsewhere. A lot of the latest and greatest developments (like React and Redux) are directly inspired by theoretical work.
There were differently thought-out solutions, but not necessarily better or worse. Perhaps the issues they thought out didn't matter as much at the time and very unlikely to matter even a little bit today, and who knows how much they got wrong and much worse. It's very hard to speculate. But one thing I'm sure of is that these things cannot be really well designed from scratch and all the problems manifest only once they are used by people. So widely used systems can only be compared to widely used systems, not something niche or unused.