Confidential is something which is not meant to be disclosed, but people gossiping call anything as such that has not been yet divulged to the public.

That era was still too early for widespread self-hosting and people were barely discovering all that internet tech. So what Jabber/XMPP offered was still neither appealing nor user-friendly enough.

Moreover, it was Whatsapp that fixed your mobile number as your username that ruined Jabber's momentum, not Google. Google Talk or Chat had never reached a notable market share.