Well, I use it on all my rigs but it's not directly what I think you are asking about.
I just use Proxmox (hypervisor) to run vm/lxc which run docker - and I just have backup images of those.
It has pros & cons but it's not a docker backup, it's just that by chance it's ok for the little use I need it.
I would go for one of the other recommended solutions but perhaps consider a Proxmox layer underneath if you wanna a full image backup of the server(s?) itself.