A few reasons.
A lot of corporate real estate is plugged into the financial system. If that loses value, it all loses value.
Then there is the fact that while some are more productive at home, many are not. Remote employees often turn into part time employees. We have several remote workers, and they are not as effective as in person workers.
Then there is the fact that perception is reality. You won’t get promoted at home. Your hiring manager needs to see you, know who you are, to promote you. Even if you are the one that is productive.
Then there is the fact that perception is reality.
There is no Company without company of people. We were built to interact.
But Office World is Mostly Dead.
“You won’t get promoted at home”
Some folks will happily take that tradeoff.
Being a manager means dealing with idiot employees—whether they work in the office or at home.
I must have turned down a dozen requests to “promote” me in my career.
And if you can do that job from home, so can someone on the other side of the planet for a fraction of the cost.