The CTO confided in me one day, around six months to a year after the promotion, that the dev deserved a fat salary raise because they were doing well with their new responsibilities -- but the CTO was worried that promoted dev would expect that kind of pay raise again in the future, when the organization clearly wouldn't be able to do it.

I called the CTO dumb and told them the promoted dev was doing well at their job for the same reasons that they'll understand that fat pay raises can be a one time thing.

Whenever I think of people leaving because they aren't getting pay bumps, I don't think of managers being stingy. I think of really weird mis-expectations and what must've happened in the past to build that expectation in managers' minds.