alt Hacker NewsI suspect the way you get to that size is having a team of 5 people doing X for Fortnite going "man, we could do our specific job a bit better if we has 7 people." Scale that to a whole corp.
Each job is justified in isolation to do a specific thing, at least at the hiring time. I suspect there aren't a lot of people thinking at a high level as you are "we have this many gajillion dollars - what are we betting on?"
Also as you get bigger you need more and more "glue" people, HR, accounting, etc. A five-man team can avoid all that, but you can't take them to 25 and have 5 5-people teams anymore. Some amount is just management.