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.
This is Google’s biggest problem, I think. They’re so flaky on their products and services, I find myself not wanting to bother trying things out in case they don’t become popular enough for Google to maintain. I saw a lot of the same remarks about Stadia, and though I seem to remember Google assuring Stadia was playing the long game, well, we see how that played out.