The kind of technical debt otherwise known as premature optimisation. If you don't even know yet that your app has to scale - and in which way - preparing for that contingency is a waste of resources.

I wouldn't qualify that as a premature optimisation. Kubernetes is de facto standard of running applications now and you get all the benefits for almost free. Premature optimisation in this case would be over provisioning - throwing more servers than you need.

K8s is "de facto standard" already? When did that happen? No doubt that K8s has a great future and I personally like it a lot as well. But to call it a standard requirement itself is premature.