of course you're OP by end game.
but as you levelled up ... the challenge was 1:1.
I played PoTD difficulty and thought the difficulty peaked at around level 5. Aside from some difficulty spikes in the first DLC, end game was way easier than early game.
I always thought the same about BG, but because of the absolute broken shit you can get, endgame is a joke. Not that I dislike this, I like feeling like a demigod after a rough start, specially when you literally are one.