Actually in this day and age scaling you code (to a moderate level) is maybe not the hardest part, I think the hardest part is to have the ressources to pay for hosting, bandwidth, cpu and ram. Thus if your model was not to provide a free app and have indirect incomes, in this case having non paid users is a major problem. But I think they should have thought about this problem before launching their app and implement anti-piracy measures.
You're right.. It's not all that hard to scale, and on top of that a single server really can support a lot of users. I built the back-end for an app in the App Store with well over 100k downloads and tons of active users.. It runs on 2 servers with a load balancer, and is total overkill. I could dispose of the load balancer and just run it all on one server.
I have a real problem with them blaming piracy for this, when there are many things they could have done to address the issue, as you mentioned.