There is a middleground, but it requires conscious effort to prop-up, support, and maintain over the long haul: off-boarding centers.
I worked for a Big Tech company that actually did this, and it made the transition a lot easier. You could still access corporate resources necessary for the transition (HR, benefits, internal job postings, training offerings, expense reporting, etc), check-in with colleagues 1:1 (who would be warned this person was no longer part of the org, attachments could be blocked to prevent exfil, etc), and still send/receive email internally (though external was blocked by default and required justification).
You can safeguard your corporate infrastructure without actually cutting everything off entirely and sending someone home to stew angrily about it. In fact, there might be (as yet undocumented) advantages to letting folks exist in that transition period on that segmented infrastructure, so as to identify potentially bad actors before they can do harm and see about mending bridges.
Of course all of that requires conscious investment in projects with no clear quarterly/yearly KPIs to measure cost or success against, so most employers will never remotely consider it.