I understand where you're coming from, but hear me for a moment.
From what I understand, all that analysis is based on two premises:
- Two (or more) opposing "forces" that should, theoretically, be human players
- The goal of the game is to win
IMO, this is the reason why that paper doesn't fit in this case (7D2D SP), specifically because:
- The AI, however good faatal can make it, can't even begin to compete with a committed and experienced player. It can be a fun challenge, sure, but has nothing to do with the level of challenge you get in a (e.g.) PvP game. That's why I don't think the PvE can represent something you'll never be able to overcome if you don't choose the most efficient tree in the game.
- The other aspect where that model doesn't work, IMO, is that this is a sandbox survival game. As long as you're surviving, YOU ARE winning. I would also add that in this case, you are already winning when you are having fun with the play style you chose.
So, all in all, this come down to how you approach this game: using a less efficient perk tree, for you, is self-deception, for other types of players is just "having fun".
I hope you understand that I'm not bashing in any way that author/article, that guy is very smart and has good points.
I just think they don't apply to my 7D2D SP game experience and the way I see "balance".
Oh, also, about "balance"... I see that you talk about balance when applied toward having "the same efficiency". My point of view, is that balance should also be focused on the specific play style you choose. Example: if you want to play as a hunter/archer/trapper, then you'll want to have fun with stealth kills, tracking and surviving in the wild. If you're a brawler, you'll want to be able to brawl your way into POIs and drink beer to get tougher and use cool knuckle dusters. Every role you play must be balanced to be unique and fun! That's the kind of balance we need and like.