I think what the OP means that using Docker you can use tools that give horizontal scaling for free (see: Cloud Run etc.)

The claim that horizontal scaling is free with Docker is simply not accurate.

Maybe it will be some day, but these orchestration and deployment tools built on Docker have enormous hidden costs.

IME, Docker takes an enormous amount of focus away from the customer problem and moves it to the how to get this mess working problem.

Now may be the right time in a given business to make that shift in focus, but to claim that it will be "free" is just misleading (IME).

> IME, Docker takes an enormous amount of focus away from the customer problem and moves it to the how to get this mess working problem.

This is the opposite in my experience: Docker lets me focus on the business problem by making deployment easier.

Docker lets me focus on cool problems like "which commands can I use to free up space on this cloud-based container-running VM, given that there are 0 bytes free, and many tools will crash if they can't make a tempfile/dir?".

At least, that's been my experience when maintaining a mess of other people's Docker crap.

> Um. Docker does not provide horizontal scaling at all, for that you need orchestration.

It does. Please take the time to learn about Docker and it's Docker swarm feature.