I'm glad you don't feel your job is that way. This book, however, is an anthropology of people who Themselves, feel that their job is pointless. You can argue that they are incorrect, but Graeber's point is -
Who is more likely to know whether a job is valuable: you, or the person actually working it?
I'd trust their manager or skip-level manager more than I'd trust them. Lots of rank-and-file workers really have no idea how they generate value for the organization. Until you've spent a lot of time managing people or at least sitting in on management decisions, it's hard to understand the kinds of concerns that drive corporate decision-making. The fact that a corporate minion thinks their job is pointless means the job actually is pointless like 10% of the time, or that the minion just has no idea how the org works like 90% of the time.
Who is more likely to know whether a job is valuable: you, or the person actually working it?