They bought WebEx for the same reason as most of their other acquisitions: vertical integration and diversified interests. It doesn't even have to work well, it just has to be a feature they can advertise, and dumb executives will assume it works and buy it. By the time they've got their hooks into you, you realize it'll take years to remove it. Pretty good cash flow for years before the customer jumps ship.
What's fascinating is that working inside Cisco, the same tricks work on them. We'd adopt a vendor only to realize it doesn't do what we want, but now we're kinda stuck on them and it costs more to replace them. It's a bog-standard giant enterprise where the left hand doesn't know what the right hand is doing. But they're wizards with cash.
Yes honestly webex may be the single worst piece of software I've ever used in my entire life. I remember having to use it for some school projects back in the day and it working slower than a snails pace. You literally could not type anything into the computer because it was so slow it would just lose letters and take 10 seconds or so to update your keypresses. Years later i had to use it for remote work for a company and it was exactly as terrible as it was all those years before. Entirely unusable. I jumped ship before covid and all the wfh stuff happened to a much much better laid out company but i always wonder how anyone managed to accomplish anything for those couple years.
My experience was different. I did not know it existed before joining a team in Cisco to work on the signalling part. Afterwards when moving to Microsoft I saw how terrible Teams was in comparison. But to this day I would love to get back to Slack if truth be told :)