However, being based on standards is more like being based on the lowest common denominator. Moxie describes the issue pretty good in his post where he explains why signal is not federated (any more):
https://signal.org/blog/the-ecosystem-is-moving/
When talking about things like encryption, RCS isn't that much better, it seems. Correct me if I'm wrong, but encryption is optional for the implementors. That doesn't seem to make it secure by default.
And it's also not Google trying to push to open standards. In the past, Google made multiple attempts to get their own iMessage and did not succeed:
https://www.androidauthority.com/rcs-google-3090142/
It feels like the campaign for RCS ist judt a PR campaign against apple.
Don't get me wrong, I think SMS is dated and I think it needs a replacement with something more modern and open that is not owned by a private company.