[quote=@Amaranth]
<Snipped quote by Decius Shade>

I thought they weren't strictly Sith and more of just Dark Jedi?
[/quote]

Exactly, they are in fact just Dark Jedi.

But you see, the Sith lineage and history are idolized by The Outcasts.

The Outcasts more or less borderline worship the Sith traditions, lineage, and philosophies, and follow them fanatically.

For lack of a batter analogy, The Outcasts "want to be just like the Sith when they grow up, and, even though they will never truly be Sith Lords, and only Dark Jedi, they still idolize the Sith and their mastery over the Dark Side".