I just confirmed that it's not working on Firefox. Google desperately needs to fix their quality testing.
Well, my guess it is more like "People could always switch to our browser, if it's not working, we will make sure it works in other browser later".
Not really, Hangouts is broken on Chrome for the last two years, and one of the Google's engineers even said in the bug report that they can't reproduce it because they still use Google Chat, so it's more like "it works for me so push it live".
Well, i hope i am right. :) Your theory would be horrible.
*edit: To be fair, mine would be horrible as well.
Reminds me of the tactics that Microsoft used with Internet Explorer. Google is not the friendly do no evil company they once purported to be.