It isn't just relationships and momentum. XKCD had an interesting what if -- what would happen if a bowling ball was blown up to the size of Earth?[1] Turns out at that scale metal behaves like a liquid.
Work at big companies is kind of like that. Once a company gets big enough, any given person doesn't really know anything. Seemingly no one is doing anything productive -- it's meetings all the way down. But the software still gets shipped. It doesn't happen the same way it happens at a startup where someone sits down and codes a feature. It happens in a totally different way, where one hundred engineers go to meetings all day and talk to QA and analytics and bizdev, and maybe commit one line of broken code a week. It takes way more people, and the production process is totally different, and it takes way longer, but stuff still happens (often quite successfully).
[1] https://what-if.xkcd.com/46/