When Zoom first came onto the scene, the other technologies you've listed had more friction than coarse grained sandpaper. Zoom was the very first to let people join meetings without a) signing up; and b) downloading anything. I don't know about all the solutions you've listed, but Google Meet for example still requires an account whereas Zoom still does not.
As more and more people use Zoom, the friction of using it decreases as well, since you can more safely assume that people have used it before and are familiar with it - if not, they can still use it without making an account, and without downloading anything (though this has become a bit harder now).
Furthermore, Zoom was also one of the first solutions to let you simply call in with your phone (and put that option front and center), which also does not require accounts or any downloads.
There are probably many other things I'm glossing over here - UX is a holistic phenomenon after all, and requires many small things to feel right. I'm not sure whether you're arguing that Zoom did not have 10x better UX than anything out there when it launched, but if you are, I can't help but think you're being willfully ignorant.