It's definitely bypassable, but it sets the floor. Not only do employers have to post hard numbers on ads, it's possible to see what other companies are paying too, so if you manager is trying to short change you during hikes you have a lot of ammo to counter argue. And you could just leave if the grass is actually greener elsewhere.

If I wanted to be sarcastic, I'd just post every job at minimum wage to 200k.

You’d probably still have to justify it somehow, like say there are stock options or bonuses that could reasonably be won.