I'm a sysadmin as well and I consider spinning up a new instance and rebuilding a system from scratch to be an essential part of the backup and recovery process.

Upgrades are fine, but they can sometimes be risky and over a long enough period of time your system is likely accumulating many changes that are not documented and it can be difficult to know exactly which settings or customizations are important to running your applications. VM snapshots are great but they aren't always portable and they don't solve the problem of accumulating undocumented changes over time.

Instead if you can reinstall an OS, copy data, apply a config and get things working again then you know exactly what configuration is necessary and when something breaks you can more easily get back to a healthy state.

Generally these days I use a preseed file for my Linux installs to partition disks, install essential packages, add users and set ssh keys. Then I use Ansible playbooks to deploy a config and install/start applications. If I ever break something that takes longer than 20 minutes to fix I can just reinstall the whole OS and be back up and running, no problem.