That basically contradicts completely to twhat the first posters said...
No it doesn't:
You do need line of sight when activated for the barrages. Cut off sectors are revealed for the duration so there is self spotting.
The person you quoted said you don't need LOS in the unattached sectors. That is correct, because the ability provides it for you. It gives you 5 less sight than you would have if a unit was standing next to the flag of a point, for ALL the points that are cutoff.
Like all expensive abilities, it can do nothing, or an insane amount of damage.
Also, how does needing LOS make an expensive ability bad? SCAS needs LOS, and its one of the best abilities in the game.