Sakhul wrote:
Because of the risk.
QFT
If you raid while defenders are on, particularly if they have nasty defensive cabal powers (ala MC), you're balancing a goodly chance of getting killed and looted against a possible HP buff and nerfing their abilities.
If you raid while no one is online, you get no buff but you knock out their cabal powers (a pretty significant hit to some cabal characters) and face very little risk of dying. Even if you DO die, you might not get looted.
This is not to say that having "fair" raids isn't a noble goal, it's just that the incentives aren't set up to do it that way. I'd personally rather have no negative repercussions (or only very minor ones such as monetary or loss of a single cabal power) for having your relic ganked - and focusing instead on bonuses for the victors.
I mean, what if by ganking someone's relic, you randomly gained (mastered) one of their cabal powers. That could stir things up!