Couldn't the traffic be LAN? Everyone keeps mentioning 'over the internet' - the device they're doing the editing on could be in a different room in the same building over gigabit++ speeds.
There is very little good reason to have this setup if you are in the same building as it.
The reason is to never allow anyone (even the editors) to have actual access to the show's files/images. Remote software can prohibit copy/paste, file transfers, and screenshots. I worked in a post facility with 100s of people all remoting in to a server rack down the hall.
What? On prem multi user remote desktop servers used by on prem users are extremely common.