I figured that would be one of the first questions brought up. You asked what is the story behind it? Well..... it is indeed a story.... so here's the deal.
Years ago, when I couldn't even break 100.... sliced everything.... and pretty much just a terrible golfer - I tried everything to improve and nothing worked. So... one day I saw an advertisement for the Heard Super Swing. It was only like $40 for the "system" so myself, my father, and my uncle figured what the heck and ordered it. Not sure how familiar you are with it but in a nutshell, here's the concept. Ten finger grip, both hands turned super strong, and a no rotation of the club face type of swing. There's more to it than that but that gives you an idea. What it did was, was completely eliminate the slice...and the "miss" becomes a hook. I used this for a year or so but eventually the hooks did me in. I did shoot some pretty good scores, including some in the upper70s, and coming from the 90/100s...this was a positive step. So.... having success with an "alternative" type of swing that got rid of my banana ball....I continued my journey.
This was about the time Natural Golf was gaining some popularity. While I never actually used this system, I did become quite engaged in an offshoot of it. Scott Hazledine was at one time, director of instruction for Natural Golf. He too ventured off on his own and created a teaching system title Ideal Mechanical Advantage. His theory was a swing based on the young Moe Norman, not the 60 year old Moe that Natural Golf copied or tried to copy. Scott's system had some flexibility with the grip and I naturally kept the 10 finger grip. The grip then became not as strong as the Heard grip but still 10 finger. It's also why, to this day, I tend to setup in a single axis manner. That is, the clubshaft and my trail arm in alignment.
Then, I stumbled across the methods/teachings of Jack Kuykendall - another supposedly Moe Norman advocate (among other things). He believed in a split hands grip. So, being the type of golfer to try anything, I started splitting my hands a little. I think over time, they have stayed separated and now, when I try a more conventional grip, either interlocking or overlapping, it just feels way, way too strange. I can't even control the club.
I have visited Erik a couple of times about 2 years ago, and of course, the grip became a topic. His thought was that a 10 finger grip was OK... but I should make the effort to keep them closer together. And I probably should do that.
You asked... and that's my story.