Thinking that Messages, which uses SMS and RCS were available, would have any impact on messaging is wishful thinking at best. Where I live almost nobody uses SMS for person to person conversations, it's mainly used for package notifications, 2FA codes, and so on. RCS isn't available as far as I know, and I wouldn't want to use a mobile only protocol controlled by the carriers anyway. It's strange that Google, a company that seems to have a phobia of native apps and wants everything done in the browser, would push for this kind of solution.
If Google had used some of their highly payed top tier engineers and at least one competent product manager to develop Hangouts instead of pushing out the mobile only, seemingly India focused, Allo they might have had a chance. Imagine being the person in a family or group of friends that convinced people to switch to Allo, you would look like a fool by now.
[0] https://9to5google.com/2018/12/02/google-hangouts-shutting-d...
[1] https://9to5google.com/2018/12/05/google-allo-shutting-down/