But some people aren't obvious slackers. They might take a simple task ('you're in charge of logistics within the warehouse'), and make it far more complex than necessary ('we're gonna need 3 teams of logistics workers who will move parts only in a clockwise direction as directed by this homegrown custom designed work scheduling system, which by the way we're gonna need a team of 10 coders to maintain').

Those people aren't slackers. In fact, to everyone else around them, they look like the best workers who achieve the most. But, by overcomplicating tasks, they in fact pour resources down the drain when they solve a simple problem the hard way.

Sometimes these workers are overcomplicating tasks deliberately (an excuse to become a team lead), sometimes they have misunderstood the requirements, and sometimes because they failed to research or take advice from others on a simpler/easier/cheaper/faster approach.

Either way, firing them is good for the business, but usually bad for morale (because the people near them see a hard worker being fired and become scared about their own position, often leading to the real best people jumping ship).

So, the common approach is to do mass firings every ~5 years, because the morale hit is lower to do it all in one go.