I think the idea here is that employers are paying people for something because they believe it provides value, but it isn't actually providing value. In terms of "should this position exist at the company" the employer gets final say, but if my boss pays me to sit alone in a room and do nothing all day that's objectively purposeless regardless of what my boss says.

An employee's perception of a job not having purpose can have a large impact on their productivity (humans in general tend to do badly when they're expected to do tasks they see as pointless for too long). Because of this, it's in the employer's interest to either explain the value an employee provides to the company sufficiently well that the employee doesn't feel that their job is pointless. If there is no way to convince the employee of that, the employee is likely either unqualified to understand their duties or genuinely doing a job that doesn't need to be done.