The document discusses different eras of software deployment:
1. The shared hosting era involved editing files, uploading, and refreshing the browser frequently with many issues.
2. The dedicated server era used Linux distros like Debian and involved more command line work like sudo and vim but still had restart issues.
3. The cloud era saw the rise of tools like Capistrano, Vlad, and Mina to automate deploys but still had restart problems.
4. Every era had issues with daemons not running, crashes, and bugs after restarts due to a lack of process supervision. Runit and systemd help address this by making applications into supervised services.