You'd think that, but once I replaced my €5 AliExpress connector cable by a proper one, suddenly I haven't had any issues with projectors any more.
Likewise, if you use an underpowered laptop, or one for which Ubuntu doesn't have proper drivers, you're going to have a hard time using Zoom.
I'm not saying that you'll never have issues (which I'm sure holds for MacOS as well), or even that you might not have slightly more issues than on MacOS (see your last paragraph), but things are definitely not as bad as comments online would have you believe, because many of those can be ascribed to issues like I mentioned above.
The same is true for Zoom: things like accelerated video streaming are universally supported on laptop GPUs, but software support is spotty for some apps/OSes. Things like screen sharing are 100% software-side.
While I'd love to use a Linux workstation (and often do), it's simply not there yet in those areas. That has nothing to do with "high-end hardware" and everything to do with less robust software support than many alternatives--including MacOS.
I guess you could make the case that because MacOS has to support fewer kinds of hardware, they can spend more time on making software support robust, but I'm neither convinced of that argument nor convinced that's what you meant by your post.