One of the problems is that many of the medical devices on hospital networks have badly outdated software, that runs proprietary applications. There should be a better job done by vendors to clean that up, but no-one seems interested in supporting this once the sale is made.

Sometimes the IT staff simply have their hands tied, and network isolation is the best they can do, at least for medical devices.

Billing and file sharing vendors should on the other hand have active maintenance contracts to prevent exactly this.