All true. I am explaining from a broad point of view. No one cares about that much detail. A person picks up an app, they send text or they send a pic, they don't care about the fine detail, they want it to work, SMS and MMS and have outlived their usefulness for the exact reason you pointed out. We want something that works and or current text apps don't anymore.
No, Google is not at fault completely. They have the ability to merge the apps, Allo, duo, messages, and gives us exactly what we want. So while they cannot control carriers and RCS they can be faulted for not giving us a good app that circumvents the problem.
That is exactly why we have so many topics and comments exactly like this one. "I moved to Android, pictures and videos are bad. What? You want me to get all of my friends to switch apps because Android is a hot mess?*