We could've been standardized on Google's messaging platform, but they kept shooting themselves in the foot with the constant rebrand & killing of messaging platforms.
(Google Talk -> Google Hangouts had a bunch of users globally back then and then Google killed it)
The current second most used messenger in US is Facebook Messenger. WhatsApp has a long ways to go to catch up in the US
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Regardless, I've never understood how some people feel superior over others on the choice of messaging platforms. It's just a tool, and what really matters is if the people you talk to is on a particular platform, not necessarily the technical superiority of one over the other.