I'm not in any way saying that you shouldn't plan for the future. We certainly have designed everything wherever possible not to get in the way of future scalin

I'm not in any way saying that you shouldn't plan for the future. We certainly have designed everything wherever possible not to get in the way of future scaling. It's just the problems you can't predict are what really get you. For example, in theory the first "designed in" limitation that our architecture has should kick in around 1.5 million concurrents. There is a service in the backend that, due to the way it is designed, could never possibly handle more concurrents than that without redesigning some pretty core internals. In reality though, when we get to 2 orders of magnitude less concurrents then that the realm starts to develop issues that we are currently resolving. So yes, don't design things that can't scale, but don't expect your designs to actually scale without serious engineering effort.