For starters, control of what uses the commoditized resources - this lets you specify & tune cpu, memory, storage, & networking allocations to virtual machines and containers.

Like start9, you’d manage proxmox from the gui, but you’re going to then tell proxmox to allocate specific amounts of different resources to start9, which will then be created as a virtual computer within your proxmox server. You’re then free to use the remaining resources on completely separate things. You can even run proxmox in proxmox if you wanted!

The hardware is still shared amongst the vm/ct’s, so there is a bit of overlap, but they mostly run in isolation from each other. This is extremely useful because for the most part, fucking with one thing generally won’t affect another, depending on what that is. Maybe you’ll reboot your bitcoind container & have to understand why that might make your local mempool instance break for a few minutes, but it’s not like rebooting or destroying your mempool vm will accidentally delete files needed for bitcoind.

The biggest benefit is recoverability - if you plan well, their backup/snapshot features will save your ass time and time again.