I think you are talking past each other about different stages of development.

At early stages you are writing some code and tests within a single component, here you are iterating with a single binary/container. At some stage a change may involve multiple components.

Once you are satisfied with your code changes you would want to run those components in an environment that simulates how they communicate normally.

In kubernetes this may mean you need your cluster and its networking components which may need configuration changes tested as part of your new feature, you may have introduced new business metrics which you want to verify are collected and shipped to your desired metrics aggregator so that you can build and expose dashboards, you may want to create new alerts from these metrics and verify that the new alerts trigger as expected, etc

You can see how you may need to run many components in order to test a change in only one. I don’t think this is bad engineering, and I don’t think it’s specific to kubernetes or “web-scale”.

That's quite a big conclusion to draw from my statement. Whether or not it is good engineering or not really depends on the problem you're solving, your team structure, your integration footprint, etc. Not everything is a custom CRUD app.