The 'Lighter' Side Of The Force
You can see echoes of Finn in the rogue stormtroopers of Zahn's Allegiance/Choices of One. Specifically LaRone, who deliberately misses shots when ordered to slaughter a village.
I like to see it as an alternative reality for the original Expanded Universe, in the original EU, Luke Skywalker, took several force sensitive beings, and trained them all to become jedi, which started the New Jedi Order. In the Force awakens (the alternate reality) Ben Solo kills all the Jedi, thus making the original events during and after the new jedi order alter.Just my thoughts.
If Snoke is an ancient Sith or dark sider (as in over a hundred or thousand years old), his corruption of Ben would be like Exar Kun corrupting Kyp Durron in the Jedi Academy Trilogy.