It's been 9 years, so I would guess quite a lot.
> Should Cisco/Webex sue Zoom for IP theft?
I mean they probably could, but this is more of an employee retention problem. If Cisco had not mismanaged the engineering department (And if they had not mismanaged the engineering department, then why did ±1000 engineers decide to leave for a competitor within a week), they would have been able to build the software in the way they seemed to feel they could at Zoom. This is Cisco's fault.
What's the point of having intellectual property if it is very clearly inferior to that of a brand new startup with a lot of the same engineers? How much is that IP worth if a significant number of your employees decide to leave to work on a product in the same space, because you can't do it right?