Only in the case where there is such a majority of the company that is tightly geolocated.

Again, AWS latency us-west-1 to us-east-1 is 70ms. That's absolute best case for one round-trip that does absolutely no work. And it's ignoring the case of anyone outside of continental US.

Add in actual server-side work, db interactions, and contention - and you're quickly looking at hundreds of ms.