They are to auth what Zoom is to webconfs: Just Bad But Good At Marketing. In the winner-takes-all environment of the web economy, they must be making pretty good money.
Back in the day many services had beautiful native clients (MSN/Windows Live, Skype pre-Microsoft, etc) that successfully delivered videoconferencing on single-core CPUs and sub-gigabyte RAM capacities but clearly it was worth sacrificing all that just to give Javascript developers a career.
Nowadays few companies besides Zoom seem to be able to replicate this experience despite processing power being more than double (not that Zoom is perfect, but it's the least bad).
I can test the mic and video before joining. I can also change my mic and video source after joining.
You'd think that both are 100% basic features, but nope. Can't do either in Google Meet or Teams...
Had to literally quit the meeting to pick a new webcam, Teams wanted to pick the shitty laptop one instead of my dedicated camera on top of the main monitor. It also wanted to use the webcam's microphone and display's speakers instead of my actual speakers and proper microphone.
The ability to put camera feeds on one screen and screenshare on another.
If you're using a laptop's built-in webcam, and you have external monitors, that makes the "video meeting with a screenshare" experience noticeably better.