There's often an issue where people do not make any progress towards becoming useful, and do not show any promise of being capable of becoming a net contributor

There's often an issue where people do not make any progress towards becoming useful, and do not show any promise of being capable of becoming a net contributor. At this point, you can fire them, silo them off the critical path, move them into other work, or just keep jamming a square peg in a round hole. But it wears on the people who have to take up the slack and do, or re-do, that person's work.