Sounds like, if you want a capable materials, mechanical, chemical and electrical engineer to write your pull requests, you'd need to pay them a salary they request. (Them in plural, because it is unlikely to find a single individual good at everything.)

Software people like to say that software engineers is super complex and difficult. On the other hand, an enthusiast occasionally makes great FOSS contribution by filing a pull request. For some reason, that is?[1] quite rare in many other forms of engineering. If it is only because of capital cost differences of building things in physical world vs building in software world (which affects stuff like learning by experimentation), maybe we should acknowledge they are a part of reason why building things in physical world is complex and difficult.

[1] Or looks rare, I may be mistaken.

That's the beauty of actual pull requests: that fat red X immediately saying a test case number 172 out of 42345 didn't pass, i.e. you're talking gibberish mister.

The beauty of publishing is that paper is patient and it may take literally centuries until someone draws a fat red X on point 172, that the Bessemer (or whatever) idea was always absolute and utter gibberish!

This is true both for the book, for the review you cite, for the comment you wrote, and for this comment of mine. It's nice to pretend you have a compiler-for-the-reality in your head that keeps predicting right every time, where in contrast with a true compiler you are wrong almost every single time.

The author isn't sharing the profits, why should people do the work writing his book for him.

If he hosted it on GitHub that would be a different story.