Obviously you are omitting the myriad of cases that an employer would like to invest in you but can't (yet) from your statement. Plenty of things like a lack of funding, individual ability, market timing, etc. prevents them from investing in you.
If I was waiting for the cash flow to move someone from A to B, and was working diligently to do so, to then have them state they are looking elsewhere for the B position, I would clearly re-evaluate my candidate selection as they may be gone by the time I get the opportunity to promote.