In 'Rally the Troops', we can see the Traveler has a shield of sorts. The Cabal probably put this up to disrupt our connection.
As for the lack of light, I personally think that is just exaggerating. I believe we've just become weaker. But "Welcome. To a world where we have less light, but still some light, but are marginally weaker." Isn't as catchy.
English
-
Actually, sony got a package from bungie with something using the new tagline for destiny 2 saying "A world without light". I think we learn to use the power of darkness.
-
So how do they destroy our equipped weapons and armor and leave us unharmed?