It's a story repeated ad nauseam, but the founder of Zoom came from Cisco, after having been in charge of WebEx there. Cisco had refused to let him do what he saw needed done to radically improve WebEx, and so he left and created Zoom and did it there.
Cisco just saw a product that was successful at the time, and a senior exec that wanted to spend a lot of money to ultimately still only have video conferencing software. They were wrong with their decision, but it's an entirely understandable one.
The weird thing is that even with Cisco $$$ Webex still isn't as good as Zoom at streaming. I wanted to watch a Youtube stream simultaneously with friends and tried it out with Webex, Hangouts, and Zoom. Hangouts was unwatchable, maybe 1-2 frames/second, but hey, it's a "free" product. Webex made it possible to see what was going on, but honestly it was pretty crappy. Zoom looked more or less like the original stream. Pretty amazing for a product that until last year was mainly known security holes.
I've been using Zoom via work for over 4 years now. It has been a stable and very good video conferencing solution for all that time. It is the first time I've honestly dealt with video conferencing software that "just works", which is a huge deal. I've never sat in meetings with people dithering about trying to get it to do what they needed.
Cisco just saw a product that was successful at the time, and a senior exec that wanted to spend a lot of money to ultimately still only have video conferencing software. They were wrong with their decision, but it's an entirely understandable one.