A.) So many customers wanted it that we couldn't scale fast enough.
B.) We ran out of time or money before we shipped.
The author appears to be worried about A, but in my experience it's B that you need to think about when starting out.
Imagine if, instead of building any of those crazy 30-node-diagrams of an architecture in the article, he'd had one guy build his entire product in a day as the equivalent of the "20 Minute Rails Blog Demo". Then shipped it via any of the thousand-odd boring ways to deploy such a thing.
He'd still have the same number of months to worry about stacking all those blocks into that unmaintainable tower of pain, but in the meantime his product would be out in the wild. Possibly even attracting the users that might one day make such a silly architecture necessary.
As it is, he'll still ship one day. But my money is that he'll never see traffic that would overload a single server.
Because that's what happens with 99% of the things one ships. The other 1% you can fix as needed. Possibly using AWS Lambda for the pieces that need it.