However while it's accepted in regional spoken US English, it's not accepted in written English, even US English.
As for evolution, language does indeed evolve but only when changes are accepted by a significant number of speakers. No matter how much you wish it, you can't simply start forcing a linguistic change on society without society agreeing. If you start to spell "agree" as "agrii" for example, nearly all English speakers will (rightly) tell you that you're wrong, you can't just respond to them with "language evolves". "On accident" is still rare enough that we have a choice to reject it and that's the choice I'm making.
Also, remember that there are non-Americans on this site (I'm one of them). To us, this is simply incorrect. We don't have exposure to this kind of US English in most of the American media we consume (TV, movies etc.).
It's a mantra that the military use. Train, train, train and fail in training because you can't fail in the real fight. If you read "can't fail" as "can't afford to fail" rather than "failure is an impossibility" you'll get the intent.
The point might have been that with access to emojis (on other platforms) youngsters no longer use the oldschool emojis. Use of oldschool emojis strongly suggests oldschool poster :)
Was a fairly hassle free process. I never spoke to a doctor and use the device for the reasons you said. Just interested in the data.