While Messages and RCS is how Google wants you to message friends, Google Chat also fits that role and the company today reminded us...
tl;dr: after pushing rcs so hard for years, killing hangouts well after forgetting about it, & hiding it from gmail, google now wants you to use its (and google allo’s) successor, google chat.
And the new one they introduced will have fewer features than the old one with no plans to get it to feature parity.