VOY fights off any of their own original enemies (Kazon, Vidiians, Krenim, Hirogen) or they get help to fight them off and the audience is "Alright, I still hate all of VOY's original creations but they fought them off and its believable."
VOY encounters the Borg and it's always "They survived an encounter with the Borg, which shouldn't have happened and they all should've died since the Borg are faster than them and their weapons are supposed to be completely ineffective. They've emasculated the Borg by not having them kill everyone."
And this is regardless of how it's done, whether they use trickery or get help or anything.
er, because the Borg are supposed to be stronger than just another enemy. Plus, Voyager's crew has infiltrated Borg headquarters before in just a glorified runabout and emerged unscathed.
the concept of Voyager going up against the Borg just doesn't work believably because the Borg are a powerful collective in their home space and Voyager is one ship. At any time, the Queen could have dispatched a handful of cubes to blow Voyager out of the stars.