That's sort of an easy mistake to make though, when one Borg cube can defeat thirty-nine Federation starships.Having everyone think of them as some "Unstoppable force of nature" instead of just a new enemy is what screwed them.
Easy way out of that would've been to explain that one Cube assimilated some alien power source that augmented it's power 1000x over and the rest of the Collective doesn't have that kind of power.
The Borg's adaptive powers are only that effective against tech that was already far less advanced than theirs. Up against anyone whose power generation capability was equal or superior to theirs, their adaptive powers would be ineffective.It's not just that. If it's a military difference you can just say, Voyager had new weapons installed that made it stand up against the Borg more.
The Borg were established to never be susceptible to the same weapon more than once or twice, and completely unwilling to talk or bargain. Voyager gave the Borg a face with humanesque motivations that was willing to talk and bargain, and made it so weapons could work repeatedly against them.
In Endgame when they had the special future armor, TNG Borg would have broken it with the third or fourth shot
And this whole "Unwilling to talk or bargain" nonsense is only good for a one-shot/two-shot foe. Not a recurring antagonist.
They shouldn't have stupidly overpowered them so much to begin with, it'd be like if the Doctor was always running away from the Daleks or Cybermen.