The delisted games dealt in subject matter that is difficult to justify.

The problem is who gets to decide what’s “difficult to justify”. That should be up to the individual, not the payment card company.

MasterCard doesn’t need to help anybody buy “games” about incest, rape, or sexual assault of minors.

That might be your opinion, but again, who gets to decide what’s on that list? If you don’t think those games need to be played, then don’t play them. It’s not hurting anyone when someone plays a video game, no matter how icky the game makes you feel. No one is forcing you to play anything.