Why do people keep saying it just works? It just works if you install their app, probably. But audio doesn't work at all in Firefox. That's not really just works for me.
I've never used the web version, but it wouldn't surprise me if it's not the same experience. The video and audio encoding and decoding stuff seems like it just makes more sense as a native app. Given the number of variables that browsers, versions, sandboxing, etc. bring to the equation, I can tell you where I'd spend the majority of my efforts if I were doing video chat: on a great native app. You have a lot more control over that experience, IMHO.
Anyway, your comment reads to me like someone who will never install it, but I would encourage you to at least test out the difference to see why it's become so popular.
So people keep saying "it just works" because Zoom has a noticeably high ratio of works compared to almost any other video conferencing software. It does not mean it works 100% of the time flawlessly for every single user ever always and forever.
FWIW, of the hundreds of Zoom calls I've had, many with non-technical people, I have yet to encounter any issues. I cannot say the same for most other video conferencing products I have used. YMMV, take with grain of salt, caveat emptor, etc.
"it just works" doesn't mean "its a superior product". I use Zoom over hangouts whenever I'm on a call with more than ~3 people, but automatic gcal integration + being fully functional from a browser means that hangouts makes more sense sometimes.
(I also don't have nearly the amount of issues you do with hangouts. The biggest problem for me is how much worse they handle crosstalk, which isn't an issue when there are only a couple of people on a call.
They have a lot more ability to ensure it works when it's their own binary. When you're relying on a bunch of browser functions, it's way harder.
The browser version is a last resort.
Latest Safari/macOS.