You defended Hangouts elsewhere. Again I followed your links and don't find things that match your explanations.
The second link is just a screenshot and I see nothing concerning 'identities' there. It wants to replace SMS and you can accept or deny? Granted, one should click on that learn more button before accepting that - I don't know what hides behind that link.
Maybe it is the first link you posted? That .. doesn't seem to say a thing about identities either, unless you mean the single paragraph about being able to select among multiple accounts, should you be signed in to more than one?
I didn't watch the video, maybe that one offers more, but so far I don't think FUD is the right term here..