Most of the villains you listed actually are weaker than the good guy/Hero. So the Hero doesnt need plot help to defeat their villain.can a villain win if the hero has killing intent?
Hashirama held back against Madara
Hiruzen held back against Oro
Jaraiya held back against Itachi
Naruto held back against Sasuke
Guy held back against Itachi
Itachi held back against Sasuke
With hero killing intent and bloodlust, Naruto would've ended 95% of all shinobi himself
But is impossible for our hero to defeat much stronger villains like Kaguya or JJ Madara without helping from the plot. No logical way.