....what? No they don't. A Fallen Vandal does not look the same as a Cabal Phalanx.
There are eight base Cabal enemies:
War Beast
Psion
Legionairy
Phalanx
Incendior
Gladiator
Colossus
Centurion
From what you quoted, I only really see 3 different opponents:
War Beast
Psion
Big units cabals
Saying there are 8 Cabals ennemis feel really wrong to me, since the last 6 you quoted behave in a very similar way and don't offer much variety from a gameplay perspective. The only thing that change is the weapon they are using and their health bar.
I mean, it's like saying Halo had like 30 different enemies because you had:
Grunt with plasma pistol
Orange Grunt
Red Grunt with Needler
Black Grunt with Full Rod Canon
Jackal with Orange shield
Jackal with Green Shield
Jackal with Red Shield
Elite with blue armor using plasma pistol
Elite with red armor with plasma rifle
Elite with black armor using Full Rod Canon
Elite with gold armor using sword
Hunters
Flood human base form
Flood human form with AR
Flood human form with shotgun
Flood human form with Sniper
Flood human form with pistol
Flood human form with Rocket
Floor human form with plasma pistol
Flood Carrier
Flood Elite form with....
And so on.
And this can be said for every factions in Destiny. They have like 3 variations of their class and behaviors, and some classes for specific species. But they still behave somehow the same way and don't really impact the encounter.
Destiny has variety for sure, but not so much actually if you look at how AI behave and their effect on the battlefield.