As the author of that "Docker is the Heroku Killer" post that was popular a couple of years ago I have to say that I agree with this.

When I wrote that article it was largely focused on the potential for Docker to create a bunch of Heroku competitors as well as a simplified development experience across multiple languages.

The businesses aren't there yet although a ton are trying. The local dev experience has not materialized yet either outside of native Linux due to performance issues with volumes that only a 3rd party rsync plugin have come close to fixing.

I still use and advocate for Heroku pretty heavily for just about any non-enterprise environment.