It's not that I don't believe you, I just found it surprising, since choke can be caused by so many things. Like this, from an article regarding choke in horses:
Causes
YUP! Lets look at it.
Chewing: Horses may develop choke if they do not chew their food properly. Therefore, horses with dental problems (e.g. acquired or congenital malocclusion, loose or missing teeth, or excessively sharp dental ridges) that do not allow them to completely grind their food are particularly at risk. In addition, horses that bolt their feed and do not take the time to chew properly are more likely to suffer from choke.
Cubes are large and often not completely chewed properly before swallowing.
Dry Food: Dry foods may cause choke, especially if the horse does not have free access to water, or if the horse has other risk factors linked to choking. While pelleted or cubed feeds in general fall in this category, horse owners sometimes express particular concerns about beet pulp. However, while horses have choked on beet pulp, a university study did not document that beet pulp is a particular problem. It is believed that choke related to beet pulp is linked to the particle size and the horse's aggressive feeding behaviour, rather than the actual feed itself. Research suggests that horses that bolt their feed without sufficient chewing, or who do not have adequate access to water, are far more likely to choke, regardless of the type of feed, compared to horses that eat at a more leisurely rate.
Cubes are dry, which is why I recommend soaking them. Dry + Large = increased risk of choking.
Foreign Objects: Horse may ingest non-edible materials such as pieces of wood. Cribbers may be more prone to this type of choke, if they happen to swallow a piece of wood or other material while cribbing.
I was just surprised that you never had choke caused by other items or conditions mentioned like wolfing down food (therefore not properly chewing their food), or horses with dental concerns. That's all! Guess I'm just one of hundreds of owners who have never experienced this problem, as I've NEVER had a case of choke.