When you start on a team, you produce negative value. On day one, you've already cost the company a significant amount just in recruiting, signing bonuses, and randomizing the other engineers who had to interview people for your position. Where I work, I would guess the break-even point is about six months to a year, so there's a good chance someone who leaves after like 1.5 years is still a net loss.

Maybe it's a good way to game the system, but don't expect the system to cheer for it. Also, if you run across someone who worked at a place for a year and they claim they completely rewrote and revolutionized a legacy system, blah, blah, etc. you should take that with a grain of salt, because of course that's what they would say. They're not going to tell you how they hustled out the door a month before the performance discussions because they knew the hammer was coming down.