You mean like an in-house metal server? Well because I need to adjust resources on the fly sometimes, or experiment with different configurations, or test upgr

You mean like an in-house metal server? Well because I need to adjust resources on the fly sometimes, or experiment with different configurations, or test upgrades on my own. That's why you use a virtual machine. If you're wondering why to use a scripted provisioning system, it's to have that code under version control and shared between developers.