That just means you don't know how to architect a machine with containers (and if you're effective in what you do, that's ok).

But it's a pretty objective notation that manually scaled single machines don't scale as well as automation.

Docker can be super simple. Like, if I want to run a Python service, that's just a few lines in a Dockerfile and a docker-compose.yml stub. Then I can trivially deploy that anywhere.

Simple to start. Yet it is more complex at run time, which can complicate (or simplify) debugging, depending on the problem.

Observability in production is where APM solutions like Datadog, Elastic, and Sentry come in; you can go from just logging errors all the way up to continuously profiling your application and beaming log files to them to correlate with metrics and database query timings.

If you're just doing a simple application, Sentry really is the way to go, while Datadog and ELK are agent-based and more intended for complex setups and big enterprises (especially in their pricing structure/infra costs).

Are you at least using Ansible or Chef or something?