Luck is probably more than likely.
In almost 40 years of woodworking I have only had kick back a few times. Each time was unexplainable. Don't know what went wrong, so I can only guess. The most memorable time was a small block of wood that hit me dead center of my chest. For a few seconds, maybe a little longer. I couldn't breathe. The pain was pretty bad for a short while. Knowing I took a bad hit near my heart and not being able to breath was scary for a few moments.
A friend of mine took a hit from a small block - dead center of his forehead. As he was passing out, he realized that he was falling face first onto the blade. Luckily, he had the wherewithall and strength to push himself away from the blade before he passed out.
Sooooooooooo, it's not always about losing digits.
Tony B Retired woodworker, among other things.
"Strive for excellence and settle for completion" Tony B