Unlike machines that can always respond to a request for synchronous communication, people are often having meetings, doing other work that cannot be interrupte

Unlike machines that can always respond to a request for synchronous communication, people are often having meetings, doing other work that cannot be interrupted, or in different time zones. All of which necessitates asynchronous communication -- even if the delay is only a few minutes at a time. You can't just take research about distributed computer systems and apply the conclusion to humans.