But on Android, you can replace the default messaging app, and that app can have access to SMS as a fallback, so it's really easy to convince people to switch. "Hey, uh, plain messaging is annoying some of us, please install this app, we can all use it, but it will work even with people who don't have it over the regular text service."
Can't do that on iOS.
It's still getting rolled out a lot of places. Google sees it as the successor to SMS and it's built into native messaging apps. I recently saw cross-carrier support get enabled locally and that made it universal enough that so far anyone I message that's running Android is already connected via RCS.
Apple intentionally doesn't support RCS in order to keep imessages from interoperating with android.
What alternative would you suggest? And is that alternative as universal as SMS?