Wrong
Google Hangouts was designed as an instant-messaging app operating across multiple platforms for its now defunct social network platform Google+
Hangouts is older than Google+; Google+ was essentially a single sign-on service with a social network tacked on. While the network had some nice features, it never really gained traction and so Google did what it often does, took what it thought worked well and put it in other things and closed it down.
Hangouts has always had very good support for voice calls and Google put some of this into WebRTC.
I only have one contact that I still use Hangouts for, but conversations are mirrored on Google Chat so that should be fairly transparent.
Biting the hand that feeds IT
