It does take some time for a new employee to figure out how to visibly contribute. Whereas more established ones have gained trust and confidence, so that they are considered fully engaged even when remote.

I wonder if a good hybrid approach would be that managers with reports having less than a year or two tenure, along with those new reports, go in to the office every day. At the end of that time the worker can work remotely. When the manager no longer has new reports, that manager can work remotely.