What seems like a great idea will deliver great heartache when you need that Time Machine backup and the only or most up-to-date copy is in a network storage location.
The heartache will start when you can’t access that network drive location, when you’re doing a system restore following a catastrophic failure. You’ve suddenly got nothing, right now, when you need it the most.
Even with the network savvy you possibly hold, being able to manually address and connect to that Time Machine location when you’re facing the need to do a restore, you’re going to be wishing for an alternative method.
Another reason why:
Speed. How much time do you have?
You’re expecting to pull a couple hundred GB’s data over your network to restore your computer, right? Compare that to a USB 3.0 drive at 5gbps and a quality network of 1gbps the simple math is 5 x faster, in a perfect world comparison.
What are the options?
Use a USB drive for holding Time Machine backups. Encrypt them, if physical security is an issue.
Backup your ‘files’ (Documents/Downloads etc) to another location (NAS/cloud). Then/if you ever need to roll back, the USB storage can restore your OS and your working data is easily retrievable via cloud or network storage. You’ll be up and running easily and quickly.