The main idea is building a single server deployment in a secure and maintainable way... and then possibly taking it to 5-10 servers at which point the Bash-only approach is less than ideal (but possible). Then you can pick a better tool of your choice (Ansible, Docker Swarm), but learning it is outside the scope of the book.

The demonstrations are made alongside the indie hackers/early-stage startup mindset. Run a single server, or possibly single server with a dedicated database.