culling the bottom 10 or 20% of performers in order to improve the overall performance of the company.
If someone isn't doing a satisfactory job, they can be fired.
But no matter how many people you lay off, you'll always have someone in the lower 10 to 20 percentile. That's just the way statistics works.
There are a variety of reasons why culling the bottom performers seldom improves the performance of the company as a whole:
I've seen management buy into the "layoff the lowest performers" myth far too often to let it go. It is almost always the harbinger of deeper, structural problems within the company, which if left unaddressed, result in the financial collapse of the company. Laying off people - even the worst performers - almost never results in a more efficient company. If you can't fire them for cause, they're more than likely adding value, even if that value isn't being measured by a performance metric. Take that away, and you take away your ability to do business.