I will throw in my .02.
It depends on how you smoke and make the jerky, a dried salted piece of jerky will keep without the use of cure because for botulism or food poisoning to occur you need temps between 40-140, time, moisture, and an oxygenless environment. That being said the thin nature of jerky that lends itself to having oxygen at all times, plus the fact that you are drying it and also adding salt and removing the moisture is why it keeps so well, its what people did to keep meat far far before nitrite cures were ever invented.
To add another layer on that, you can dry and make jerky in dehydrators and smokers at temps around 155-160, because the jerky is so thin, you will leave the danger zone of 40-140 well within the 4 hour time window, and the rest of the time held above 140 until it dries assures no baddies can take hold in the meat. So yes, being conscious of getting it dry and the temps you are running safe jerky can absolutely be made without the use of cures. As said above however, if you are looking to make a stick with moisture in it like a slim jim or something, a cure is a must to make it keep.
That said, I use cure in all my jerky's since trying it about a year and a half ago, because I find it changes the texture and flavor of the meat more to my liking. The jerky I have made to this point has always been ground and extruded through my jerky cannon, and there has always been a very fine line between "done" and "too dry" to where it would crumble apart when you bit into it. The cure extends that window, and gives me a nice chewy texture. It also allows me to leave more moisture in the product if thats texture I want without the fear of spoiling. I also feel better about leaving a good portion of the salt out of the recipes I use for a healthier stick, and I make some special low sodium versions (only about 1.5 tsp for 6 pounds of meat plus the cure) for my uncle who is on a low sodium diet.
Sorry about the novel, but I have made jerky for years without the use of cure, and now with the use of cure, so I thought I finally had some experience to give back to the community.