I'm not sure what people want these days: people are angry that they have successful products that people use more than competitor's prodcts, and also angry that they have unsuccessful products that are shut after failing to gain traction.
Mobile is all about power management. Apple got that right and really nailed the UX.
I don’t think Google knew that playbook at that point. Maybe Rubin did but even MSFT blew it.
None of that matters anymore, because Messenger/IG/WA are all mobile apps that most people probably dont chat as much through on a desktop/laptop. But at the time, it gave people a compelling reason to have the messenger product open on screen. Google Talk was similar, being overlayed over Gmail, but google squandered having a Talk bar over the bottom of every google property. Yahoo as well. Yahoo News should have had messenger across the bottom of the screen.
On the mobile front, FB Messenger sort of won out because people started to like iMessage, but there was still a need for a cross platform alternative. I believe Apple could have prevented FB Messenger from being a thing, had they released an Android client along with a browser extension. Apple's best move was releasing iTunes for Windows, something they are scared to repeat, and shouldnt be.
I wonder what the numbers are on WhatsApp vs FB Messenger, because people of all socioeconomic levels, languages, ages, country, and tech literacy use WhatsApp in my experience, whereas only Americans of a certain age group use FB Messenger.