Like the author, I hope to see some kind of open system get adopted. 3rd party apps are popular in a lot of places but they are the wrong solution because you rely on a company offering a free service to behave. In Japan, the dominant messaging app LINE has been struggling to get spam under control, and has had some recent security scandals with personal information being viewed by a Chinese affiliate and user payment data being leaked on GitHub. Because of these and other issues, some younger users want to drop LINE completely and move to alternatives like Discord and iMessage, which is bringing fragmentation back.
If a centralized messaging app became dominant in America, it would likely attract antitrust attention too. These apps have to make money somehow, usually by selling emoticons, charging business users, or adding features like payments. I doubt the current FTC would be pleased if Meta realized their old ambition of creating America's WeChat.
RCS may not be perfect but I would rather see Apple adopt it if the alternative is nothing. The messaging experience for America would be a lot better for it. Google's rhetoric around this seems to indicate there's no current interest in collaborating to build a better standard, so it seems to be a far off ambition.