With screen sharing, I have far more presentation flexibility than when uploading slides as I'm no longer limited to slideware. However, occasions may arise where I want to do something - perhaps I forgot to disable Slack, or want to set something up - that I'd rather not have the audience see. The ability to pause my screen share, freezing on the last shared frame, would be very useful. (I'd mention that I've used this feature on many other webinar / virtual meeting platforms but I can't claim that means it's popular with users.)