For myself, I rarely make decisions based on improbable "mights" and "coulds."
People are killed in automobile accidents every day, and there's nothing to say it can't happen to me...but I still drive.
I'm not advocating walking and knitting particularly (though I've done it on rare occasion, browsing through a gift shop, as a matter of fact). But just like anything else, with proper precautions, there's no reason it can't be done.
And if one takes your reasoning to its logical conclusion, one shouldn't go to a knitting group, either, since one might trip and fall, thus impaling one's heart with a knitting needle.
I'm not trying to convince you to change your views, of course...just sharing that there are more ways than one to look at the situation.
I'm Knittermom9 on Ravelry