From what I've read above 150 people [0] things start to break down a bit. Social relationships and coordination break down. You no longer know everybody, decisions aren't based on trust anymore, you cannot maintain a flat hierarchy, etc. The structures that support the "behemoth" with tens of thousands of employees spread across the world make it more rigid. With hundreds of teams, products, services, and managers office politics becomes a very real thing and people start having their own plans and ambitions. People stop pulling together towards the single goal because there is no single goal anymore.

And having lots of teams "innovating" is also not that great. You'll just end up with a stack of 100 great ideas on your desk but only 2 that might make money. Your job is to guess which 2. Any decision you take will be heavily scrutinized by everyone in the company and shareholders. You may just go the safe way, that worked over the past few years and put a bonus on the table.

A 10-20-100 person startup with everybody in the same office and a very flat structure will be a lot more agile. The people are all there for that one single purpose, and the dynamic is quite different. Once the goal is reached many just move on. This provides a very different motivation vs. the typical corporate employee.

[0] https://qz.com/846530/something-weird-happens-to-companies-w...

Even if you know what is coming, that doesn't guarantee you can outmaneuver it. When you are dealing with thousands of people, contracts with hundreds to tens of thousand of customers, and infrastructure based on the assumptions that make your existing business tick, a fundamental change that costs a new competitor $0 to make because they don't have any of that built up stuff could costs a fortune for you to counter.

holding the place of an incumbent has advantages and disadvantages. Sometimes you can't leverage the advantages, and that's when a company can get buried by the upstart the worst.