Google seems not interested in interconnected third party RCS hubs anymore.
The current situation means that people who are directly connected to Google's own Jibe infrastructure can message carrier-operated Jibe deployments. But they can't message third party RCS networks or vice-versa.
Pure speculation: Google got frustrated with carriers moving too slowly even after acquiring Jibe. I understand carriers not being compelled by Google's lack of vision for mobile messaging then. Especially given that Apple won't give a damn.
A few years pass and Google decides to pivot their messaging services once again, and that now is the time to push RCS for real. Google managed to convince big carriers on several continents that Jibe is the solution. And they probably think the small ones will eventually cave in.
This is only speculation, but it's Google. You don't get promoted for making an existing messenger work, or work better. Better to abandon it and join a team making a new messenger.
The current situation means that people who are directly connected to Google's own Jibe infrastructure can message carrier-operated Jibe deployments. But they can't message third party RCS networks or vice-versa.