I think you’re both right, even if I’d guesstimate the situation you encountered is very, very rare.
You should make architectural choices that CAN be scaled within reason, on demand and ideally incrementally. That doesn’t mean you need to build your app on Kubernetes and automate welcome emails, surveys, metrics, A/B testing etc. But you probably shouldn’t build on top of fundamentally non-scalable systems either.
This is provided you’re in an environment that can reasonably scale to 1M users or whatever, which isn’t true for all domains. Say B2B where that last B is only 10000 people world wide.
You should make architectural choices that CAN be scaled within reason, on demand and ideally incrementally. That doesn’t mean you need to build your app on Kubernetes and automate welcome emails, surveys, metrics, A/B testing etc. But you probably shouldn’t build on top of fundamentally non-scalable systems either.
This is provided you’re in an environment that can reasonably scale to 1M users or whatever, which isn’t true for all domains. Say B2B where that last B is only 10000 people world wide.