The thing about scaling is that you can't justify the engineering involved in overscaling until you're reasonably sure you'll need the capacity. Otherwise that'

The thing about scaling is that you can't justify the engineering involved in overscaling until you're reasonably sure you'll need the capacity. Otherwise that's called overengineering. Managers get fired for approving spending on things like that when the demand does not appear. It's also hard to simulate real traffic because they don't always behave how you predicted they would. Also, your system gets more and more complex as you scale. More monitoring systems needed, more attack vectors to watch for, deployment systems, backup systems... Imagine the security level coinbase needs to have. It's somewhat unprecedented since a hack could make off with a lot of valuable assets in an instant. (even just from their hot-wallet) You saying scaling is solved makes me question what you think their infrastructure looks like. It's not just an AWS loadbalancer with some shards behind it. It's A LOT more complex than that.