By that logic, companies shouldn't offer raises.

A company cannot assume that someone is "willing to settle" just because they accepted an offer. Good companies try to proactively keep people, and part of that is making sure their compensation roughly keeps Pace with the market. By the time a company gets the signal that the "maintenance rate" isn't it's too late to do anything about it.

Companies who want to keep you need to offer you enough that stay. You can skip raises to keep people for a few years, but they will remember that and expect you to make it up latter. (the ability to keep your paycheck through a downturn - and thus house and local friends - is valuable) Eventually employees catch on that their pay is significantly less than they can get elsewhere and they will leave. It is better to proactively give raises to everyone so that they don't go looking: replacing someone who leaves is going to be more expensive than keeping them in general.

> If you are willing to go through the process of finding a new job, someone will pay you more

Be careful, though - there’s some cartelization/collusion going on. If you change jobs too many times, that’ll be used as a strike against you, and a reason to offer you lower pay.