Your comment is wrong in a few ways and suggests using a LXC which is way slower than docker or podman and lacks the easy setup.
Proxmox is good because it makes it easy to create VMs and setup least access. It also has as new of kernel as stable Debian so no, its not terribly out of date.
If you want to suggest that someone install Debian + Docker compose that would make more sense. This isn’t a good setup for more advanced setups and it doesn’t allow for a not of flexibility.