SnapCenter requires a resource group before it can backup a VM. We do not have per-VM resource groups, so when we periodically want to create a per-VM backup we first have to create and configure a resource group, put the VM in the resource group, then select the resource group and execute an on-demand backup. Way too much effort. Plus we have to cleanup these one-off resource groups afterwards.
Never had to deal with the resource group overhead with the old SMVI - we just right-clicked the VM and selected Backup Now and it would backup the VM. Way less effort than SnapCenter.