Chaim Gartenberg, of the Verge, has chronicled many of Google’s efforts to build a universal messaging app for the past sixteen years, and it does not include every possible example. For instance, there is a separate messaging client built into Google Photos.
For all of the ways Google is great at web services, it is shocking how poorly it has handled instant messaging. I would love to know the inside story of why there are so many disjointed and failed attempts to launch such a seemingly straightforward platform-level feature. It seems like something Google’s engineers ought to be able to sort out if they had some way of communicating the problem.