This is part of it, but it's also true that in a lot of massive enterprises there is an absurd amount of inefficiency that leads to people effectively having nothing to do.
I had one such role at Splunk, pre-acquisition, which had a mere ~2k or so employees at the time. My entire office was effectively doing nothing; we were the result of another acquisition and management had no idea what to do with us. More hours were logged at the foosball and ping-pong tables than in front of an IDE. I'm not even exaggerating. I left after 9 months because I was bored; I did not write a single line of code that got used in any real application, internal or external.
When I went to AWS, it was closer to what you're describing; it took a lot of work to do seemingly very small changes for the reasons you mention. But I would never say that my team there had too many employees doing not enough work; everyone was busy all the time, it just took a lot of work to do very small changes.