Well a problem with most games, and indeed fantasy writing, in particular is the darn "hero's journey" which has been taken far too literally by too many writers.
Having said that, it's really difficult to create a protagonist in a game without going through the motions/chapters involved.
One of the reasons that there is just very little new original writing, because writers often use it as a template.
But that's not The Witcher's problem at all. It's a power fantasy not because you go from farmer to savior, but because you start as the studly professional and only ever have your mettle proven again and again. Only BioWare games are so structurally consistent, and even then, it's usually the player's decision to have their character follow hero's journey so strictly. I don't think you can even find especially redundant plot points between New Vegas, Pillars, and Tyranny. As RPG, their progression will feel similar, but you'd be remiss if you said they were all the same, and you'd be especially wrong if you said they were just following the hero's journey.
My problem with fantasy writing in games is that they can't follow the hero's journey. Not properly anyway. Even in a game like Assassin's Creed 2 where the narrative quite clearly follows the hero's journey, the player never feels the same emotional highs and lows as Ezio. Your progression through the game is a fairly consistent upward climb in power. The actual hero's journey can only be felt sympathetically through protagonist, not directly through the mechanics. Very few games, and even fewer RPG are bold enough to take from the player and make final battle not just an obligatory outcome of the player's acquired power, but a victory earned in desperation as per the hero's journey.
Honestly, if you're finding the hero's journey, it's only because you're not looking hard enough for quality fiction or you're working especially hard to ignore intricacies.