The fandom/hatedom says Voyager ruined the Borg, all the way from their first appearance, and never once got them "right".
The first major appearance of the Borg in Voyager was "Scorpion" (the corpse in "Blood Fever" and the breakaway group in "Unity" being nothing but standalone appearances that just served to annoy the hatedom because they still hated the stories regardless), and it is in this episode we're shown explicitly that the Borg aren't invincible nor are they the strongest race in the Trekverse. Thus, this is where the Borg's "fall" began because the story dared to show them as not utterly invincible and thus they were not done "right".
Audience says they never got them right, all the way from first appearance. "Scorpion" is first major appearance, so by correlation this story is not getting them 'right' and starts their 'fall'.
Its up to us to dissect the story as to why they feel this way, and I presented my reasons. Mainly that they're a bunch of hypocrites who liked it at first and later turned on it because it wasn't 100% what they wanted (a 100-parter).