it's funny that you felt the need to point out the first part of my argument and forgot about the second one.

impact (feature $value * users using it) / change rate (frequency * volume)

is a full enough overview of an engineer's output in a crude manner.

if you implement a feature that makes 10$s per user for 100M users in 2 lines of code you're the best developer out there..... if you write 10000 lines of code to ship something that makes 0.005ct for 100 users ... you should not be employed.

As an engineering manager I advice every developer to find a way to learn to measure their output because that is a good way for them to know their value (ask for a raise, move to a different company ...)