Eskilius Quinn said:
He probably is part of the direct line from that Phineas Gage. I mean, a rail road spike going through your head could explain why every Black Crusade has been a botched mission. Hell, the last one couldn't even get past Cadia.
No, Failbaddon is the reason why the Black Crusades have failed.
Abaddon's "failures" are a misconception, brought about by a lack of understanding of his immediate objectives as opposed to his long-term goals.
His long-term goal is to see the Imperium crushed and trampled, the Emperor cast down and obliterated, and the galaxy burned.
The individual Black Crusades are not witless attempts to achieve that goal over-and-over again, but rather serve specific purposes in a grand plan many millennia in the making, each moving one step closer towards that goal, any of which would see a Champion of lesser ambitions granted apotheosis. For example, the first Black Crusade saw the Daemon Sword Drach'nyen claimed by Abaddon, while the 12th allowed Abaddon to claim the Blackstone Fortresses and test the Planet Killer.
Also, technically, there are more Black Crusades than the thirteen that Abaddon has inflicted upon the Imperium; other powerful warlords have managed to muster massive forces to assail the galaxy in the form of Black Crusades.
Writing Credits for Fantasy Flight Games: Into the Storm, Edge of the Abyss, Battlefleet Koronus, Hostile Acquisitions, Black Crusade Core Rulebook, First Founding, The Jericho Reach, The Soul Reaver, Only War, The Navis Primer and Ark of Lost Souls