When it comes to fluff jobs, it comes down to if it's planned that way, or it's a guy purposely trying to be lazy and fly under the radar.
How or why any company would want to overhire as a waste of money who knows. But reading articles, some industries like tech who have tons of money supposedly do that on purpose. They cast a wide net hoarding employees because it makes them look bigger and better than other tech companies having more employees, and if you overhire the company also hires more good workers. Then they'll figure out how to weed out the crappy ones later.
I dont know how true that is, but every company I've worked at is pretty lean in traditional office depts like sales, finance, marketing. I've never worked at tech or consultant companies.
As for fluff jobs where people dont do much, that can also be an employee thing. Whether it's a bad boss not keeping track or a worker floating around disappearing in a giant office it can be that too. All regional head offices I've worked at have office staff probably no more than 200. Took a guess there as some involved lots of different divisions I'd never talk to people there. But in no way is it some 2,000 office staff tower. When there's only 200 people it's already way too many to see walking arounnd where you dont know everyone. So for any big companies with giant towers and any bosses are in charge of 50 people it's probably a pain in the ass to track whats going on.