Anyone looking at their situation is probably saying "with all the resources they have, they should be able to build a system that could stay up." This is true. Its likely that if they could start from scratch, their team could put together a system that would be able to handle the traffic they are seeing and expect to see in the future. The problem is getting the legacy systems to the point where they can scale. It's one thing to have a platform that handles 10s of thousands requests per day. Now convert that system into one that handles 100s of millions of requests daily. Thats a tall order.
Developers which are involved with a product early are typically more interested in building a viable product, not getting it to "web-scale," and rightfully so.