But, if we can assume that the "rare talent" is anything other than straight out of college, they will have discovered that they are a rare talent, be aware of it themselves, and barring some sort of crippling neurosis, want to cash in on it. They might not even be skilled at negotiating... they'll just be aware that they have leverage.
We might even phrase the problem that way... that it's not so important that they have "negotiating skill", as it is that they have "leverage awareness".
But that said, not every company is trying to hire the best people. As you note, they're expensive.
Once an HR culture develops, anything sane or intelligent probably goes out the window.
I guarantee when Google hires someone like Ken Thompson, they do not get the normal Google hiring experience.
That said, the author of Homebrew would be the top authority in the field of OSX package management yeah? I mean, Apple hasn't even bothered to create a competitor and yet every tech bro at Google using a MBP is going to need to install and use it..
If there is a one off person who can command a higher salary, its unlikely they alone will make a huge difference to the company anyway.
If there are a lot of people who could command a higher salary in that role, the pay is too low.
Overall it seems like a pretty good system. You could argue that the current system favors people who are good at negotiating, and not necessarily more skilled workers.
IME, talented people can spend an absurd proportion of their time bickering about how ${other_talented_person} makes ${trivial_number}/year more than they do, all because they're ${some_trait}.
Overall, I could imagine this filter being both good and bad. I'm not confident whether it nets out good or bad, but you can't argue it's not a dramatically simpler system, and simple systems are often surprisingly better better. :shrug: