Why does Zoom need calendar permissions?

I agreed to a Zoom meeting today and clicked the 'add to google calendar' button. I was surprised to see a permissions request to give Zoom write access to my whole calendar.

Why would they do this? .ics has been around for a good while and was really what I was expecting. But sure, Zoom, go ahead and have my calendar so you can add this one event on one day for one hour.