The overhead savings alone would make up for loss of productivity.
Offices are expensive. Without even considering rent and leases you have: utilities, you have cleaning, you have security and you have other risks that come with people being in close contact with each other.
Then there is the expansion of the labor pool. You go from the region of the office, to THE ENTIRE WORLD. the challenge goes from finding the right fit from a few candidates to finding the right fit from a lot of candidates. You can hire a person who needs accommodations, without any extra work on your part because they have taken care of that themselves at home.
Then there is the kaisen: fewer steps to the toilet, fewer steps to get water, fewer steps to go to meetings, less production loss from meetings.
It is really telling that management is NOT seeing these benefits.