Pointless jobs exist because of inefficiences. Someone higher up couldn't be bothered to automate it, and there isn't enough oversight of the budget. An entrenched interest (like a no-longer-needed union regulation) is too hard to fight. Etc.
But capitalism is the most marvelous machine for removing inefficiencies, and therefore removing pointless jobs. Why? Because the owner/capitalist will make more money when they're removed/automated. It's easy to say McDonald's cashiers have pointless jobs, and they're being replaced with kiosks. Or taxi drivers with driverless cars. The same way the original human "computers" were replaced by calculating machines. The process isn't perfect and certainly isn't instant, but it happens and is relentless.
Pointless jobs decrease over time. And trying to claim that they're rising, as Graeber does, is simply disingenuous and dishonest.