It seems to be the same in every company. Layer upon layer of managers and supervisors that don't actually DO anything.
Companies would be so much more efficiently run without them, so what causes this?
EDIT: I think I might have something of an answer here thanks for @ABigguhPizzahPieh 's comment/video they posted. So, the notion of "robots are going to take our jobs" has actually already happened, and it's been happening for decades. There's just not enough work to go around for everyone. But reducing the work week from 40 hours is obviously unconscionable in capitalism, because working people aren't allowed to have nice things or better lives, so instead there has grown a massive layer of managerial and clerical type "workers" who are paid to do nothing for 40 hours a week and are miserable for it.
I like this idea that they exist as a buffer between workers and the real bosses. I mean, that is literally what a manager is I guess, lol.
I was also going to say something similar to your other point about the system requiring a certain amount of the population to be working/earning (and regurgitating those earnings back into the economy). If managerial bloat didn’t exist, capitalism would probably have to create it.
Another potential answer to OP, modern capitalism requires an intense amount of logistics for all the moving parts to work together, I’m sure the explosion in PMC type positions is also somewhat attributable to that.