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 :)