Pretty obvious that some builds are stronger than others. To be fair, lone wolf is a strong talent for sure, a duo with this is stronger than a full team (better gear, faster powerspikes etc)

And you played a weak ass rogue, imagine if you played your Fane deathknight with a godly ranger.

Just like you, my first playthrough was a bit chaotic : not impossible, but I needed to cheese a lot of fights. For my fourth playthrough, I did a Fane necrowarrior/Lohse ranger.
This fucking witch/necromancer in act 1 (the one with the dragon) ? 4 shots from the ranger. The void miniboss in the forest ? Same.
Alexandar/Voidworm ? I cursed that fight the first time I did it. With this comp, 4-5 shots Alexandar, rape the rest, finish the worm, finish the range. No cheese needed, just raw power.

That's the fun of the game : finding the most op build. Divines bless rangers.