It's a 'softban' versus prohibiting people from playing outright. Instead of pulling 'undead' (how the series refers to its protagonists) from a general population, it's grabbing them from a comparatively smaller pool of other players that've been deemed cheaters for using DS2fix. As Kotaku reports, the players aren't hacking in a nefarious way, they're just using a patch that makes the game work better on their platform of choice.
But there's a twist this time: Players installing the popular 'DS2fix' softmod that addresses weapons durability glitches and save corruptions have found that they aren't able to easily summon other players into their game for help or adversarial combat. This apparently extends to the recently released Scholar of the First Sin as well. The vanilla versions of the first two games weren't unplayable per se, but if it weren't for the enterprising community of modders around the franchise it'd look and run kind of, well, crappy.
The Dark Souls series' relationship with PC gamers has been contentious at best.
