Hi,
one benefit is, that no new VMs will be migrated to that host by DRS.
If otherwise you shutdown VMs, that host suddenly will have tons of ressources free to use, so DRS might kick in and migrate new VMs to that host.
On the otherside, putting the host in maintenance mode might even save you from having to shut down VMs at all if your infrastructure is designed for it:
If you have a stretched cluster, or different power fault domains in one DC, you might experience a power loss on let's say half of your ESXi hosts in a cluster. If your second half of the cluster has a seperate power source and is not affected, putting the soon-to-fail hosts into maintenance mode and let DRS evacuate the VMs, is the quickest way to shift your VMs over to the other hosts.
Tim