This is just another reason why I love project based consulting more than FTE. The incentives are properly aligned. Adam Smith would smile.
Personal experience - in every single work I've done (roughly 10 customers/employers, perm+consultant) in 3 different countries, there was/is always room to grab more responsibility, more tasks etc. State of IT usually just a variation of a term MESS, with some technical debt here and there, everywhere. You work harder, solve more, take more responsibility and your career progresses along (or you go to place where it does faster).
But with this might also come 9-10 hours at work instead of 8 (plus lunch), company phone which is there just to remind you of the work when you're not in, maybe more weekends screwed up and so on. Even in otherwise very work/life balance oriented employers.
Want another advice? When having a formal talk with your boss, tell him you want a raise, but you don't want it for free, rather bringing added value. Define clear terms what is expected from you to get there, fulfill them and watch the magic happen :)
(Just imagine a project worth $X with two lynchpins, both of whose absence would tank the project. Both can cause $X in damage, but you obviously cannot pay each $X)
Either by increasing their title or pay as they are that critical, or by not distributing the key knowledge around so that everyone is dispensable.
This is actually a fantastic idea, for both sides.
Jesus that all sounds so ridiculous to me. That's a funny shell game around admitting that someone was more valuable than you were paying them, and then guess what - lots of other people are.
If the argument is "But she isn't always this valuable.. she's just this valuable on this project" then attach a financial incentive to the project.
Sadly, I don't get the sense that Ben is suggesting that there's a problem with not compensating commensurate with value here or with depending on the employer-preferential taboo of the secret salary. He seems to just argue you should let this engineer walk and the project die.