Well, being a typist for my occupation,I can say that I would probably never in my life text for fear of damaging my thumb muscles. All of that activity cannot possibly be good for the joints surrounding parts of the hand. I would assume that trying to cut down on cramping of the hand is why people started to make these shortcuts, simply to save time and their thumb.
this is s/t that bothers me 2 no nd its craz that ppl cant b botherd 2 rite w normal gramer like thay lern in skool some1 i no seems like he 4got how 2 spel and makes mistakes at work al the time!