As always, it depends. Lots of people wish they had Facebook's challenges when it comes to scaling. 99% of applications simply don't.
I've never seen a company I've worked with go for 'fancy' infrastructure because they needed to. It was always because they HOPE that they need to. Granted, re-engineering your application / architecture for scaling is expensive, but not as expensive as building the wrong thing in the first place.
They should all have started off with a monolith and grow from there. I mean in all those cases we had just a single, 'monolithic' front-end without any problems.
I've never seen a company I've worked with go for 'fancy' infrastructure because they needed to. It was always because they HOPE that they need to. Granted, re-engineering your application / architecture for scaling is expensive, but not as expensive as building the wrong thing in the first place.
They should all have started off with a monolith and grow from there. I mean in all those cases we had just a single, 'monolithic' front-end without any problems.