The problem is that the job market is a market for lemons on both sides.
From the employee side, I have no way of knowing whether I've actually found something better. It could be that I've just found a company that interviews well or that got lucky enough to avoid putting foot in mouth long enough to get me out the door.
If I'm in a company that's good enough and am not sure I'll be able to land a job six months from now, it makes very little sense for me to even start looking because I know that any new job I find might be a lemon, even if it looks better during the interviews.
From the employee side, I have no way of knowing whether I've actually found something better. It could be that I've just found a company that interviews well or that got lucky enough to avoid putting foot in mouth long enough to get me out the door.
If I'm in a company that's good enough and am not sure I'll be able to land a job six months from now, it makes very little sense for me to even start looking because I know that any new job I find might be a lemon, even if it looks better during the interviews.