Maybe significantly dangerous for you, the person doing the walking. So yeah, you could walk off a cliff while texting and die. But if you look at the damage you might inflict on others then the difference is off the scale. Think of the difference between walking into someone at 3mph with your (I'm guessing) 160-240 pound body made of bone and smooshy flesh, and compare that with hitting them with a 4,000 pound car made of hard metal, going 35-60 mph.
I feel fairly certain that you'll never inadvertently kill anyone by texting while walking. But while driving? It could easily happen.