It just doesn’t make sense, it worked almost identically to apples iMessage when the person was also on Android, integrated nicely with Google Voice, had a web interface and they could have just implemented RCS, instead they made allo/duo, killed those off and now we have messages, which is fine but is just sms and RCS… Just seemed like such a waste of effort to do all of that when you already had a working product with integrations already built out.
Google is infamous for allowing valuable products to wither and die for no externally apparent reason. Hangouts, more than most was a major strategic error in my opinion.
Of course if they hadn’t screwed it up third-party messaging options might be even less popular, and that would be unfortunate.