Joe the Data Scientist says that if the app dynamically does X then that could be worth $10 million a year. Steve the product manager says his change could be worth $1 million a year. And so on and so on. Most are wrong, some are right. If you have a small team you'll never implement any of it so you won't know. If you throw people at it then you can test all those things. And when your company makes billions a quarter it doesn't take much of a revenue lift to pay for a few dozen teams.