Morality is whatever is culturally accepted and expected. Since culture can change with time, so does what is considered moral (and legal). Owning slaves was once considered moral. A husband forcing his wife to have sex with him was considered moral. There were many situations where killing someone else was considered moral or even honorable.

Extreme behavior such as described by XOP has always existed and was always seen as problematic because humans are social creatures; as such, we understand that being friends with someone who does something extreme is very likely to make people guess we are also into it - guilty by association. "Oh, so you're still friends with that criminal? I bet you're an accomplice!"