Time travel is only usable in thr vault of glass. The Cabal are weak compared even to the covenant. The ghost said the cabal blow up moons for getting in the way but the forerunners do the same thing to solar systems. The flood are way above the hives worms. They can easily destroy the dreadnaught in one go with a star road. The Vex can also get logic plauged by the flood one void walker is nothing compared to a city busting war sphinx