That ain't their arrogance. Their arrogance is declaring all browsers other than the single one they tested to be "unsupported" and not even worth attempting to use with the app. It's one thing to warn against untested browsers; it's another thing to outright prohibit them and kick you back out to the homepage (after collecting my email address with which to spam me, no less).
If it's more a matter of some specific thing(s) that Chrome has implemented and other browsers haven't, then it'd be nice to be upfront about what that thing is so that those of us on non-Chrome browsers can bug e.g. Mozilla and Apple about it - and it would further be nice to actually test against the existence of that thing rather than gatekeeping the user agent string like it's 1999.
May be we should just got back to native apps? Hell, native apps that do not connect to the internet. That'd be glorious actually. Problem with browser based apps is that you have zero control over versioning. Server serves, you get the fix. No option to request a particular version of the app. Don't like the new version? Tough luck. Server issues? Go outside.
You know there is something to be said about code/binaries residing on your computer. Call me old fashioned.
What we need is a new app runtime with a unified permission-based API across platforms. All the OS-agnostic parts of that runtime would be a huge pain to develop, so all platforms would probably settle on a shared open source implementation and only implement OS-specific "adapters" for the native stuff.
What I've done there, is reinvented Electron...fuck....