Because then it'll jump at us after hiding for so long

I've got the sneaky suspicion that the Cabal may be another race originally from Fundament. -they do come from a high gravity world. -their marching orders are "ancient", according to grimoire. -a couple pieces of grimoire make references to a Valus somethingorother executing officers and making changes to their 'marching orders', as the Cabal have not had any contact with the Empire in what seems to be a very long time. -They are indeed running from something, while at the same time their tactics, weapons and armour seem to be well suited for use against the Hive. - They are highly interested in Vex tech, something the Hive haven't bothered with, and the only Fallen who cared much for it were the House of Wolves. They're either interested in FTL travel or in copying the whole VOG/bootleg Oryx thing. -the only real instance of the Cabal engaging the Hive is on the Dreadnaught. -they are prepared to drop Phobos onto the surface of Mars in the event they are overrun... the Vex do not seem to be such a problem for the cabal, and it has been inferred that the Fallen aren't much of a threat at all. That leaves the Hive... but it's anyone's guess, really. They are also prepared to annihilate the inner Solar system in an attempt to destroy the Dreadnaught. Now mind you, the Cabal/Empire is likely not the same species as the uncorrupted Hive on Fundament, as their lifespans are ~10 years. Cabal have very long lifespans, as is mentioned in grimoire. What do you guys think?

Play the shield brothers strike another three times to learn a bit more. Cayde opens up

Because each species is unique and the dlcs are not "theirs".

The Cabal will get their chance in D2 when they -blam!- up the city.