Huh. I don't recall ever seeing that one before.
I encountered it in some video-game designer blog or something quite a few years ago, I believe the article was actually primarily about "ludonarrative dissonance," which I had been comparing/contrasting with the muddier idea of "dissociative mechanics," but it did touch on that definition of balance.
I found it helpful, because it precludes the reductive idea that "perfect balance" would be a choiceless game where all players are identical under the rules. Instead "perfect balance" becomes an (obviously impossible) game where you can do literally anything you can imagine (unlimited number of meaningful choices), without in any way obviating what everyone else is imagining (all those choices are viable).
That and the qualifier of
meaningful clarifying how balance always has a partially subjective aspect.
I'd think that these days, around here, talking about choices is more about "agency" than "balance".
They sound like closely allied concepts, yes. An imbalanced game will likely lead to some players having more agency than others, like pemerton said, "
mechanical capacity enjoyed by players, in virtue of their PCs, to impact the fiction of the game"
We might sometimes talk about "balance" in terms of adventure design as well - in the GM is throwing really powerful opponents that the PCs can't handle, we might call that an "unbalanced encounter"
Sure, in D&D, the distinction between say, Class Balance, which the game had attempted from the beginning, and generally hasn't delivered, and Encounter Balance, which 3.0 (or maybe late 2e?) first attempted as CR, with a low degree of success that 5e has not improved upon, much if at all.
Encounter Balance is a separate idea, as it's about DM tools more than player experience (oh, it affect player experience, certainly!). That is, encounter balance helps the DM (or
module adventure designer) create an encounter that is as close as possible to the level of challenge he intends. Bad encounter balance means an easy encounter TPKs, or a nigh-unwinnable one gets steamrollered. Obviously, imbalances experienced on the player side feed into that, too, as a party that leverages the game's imbalances to their advantage is likely more powerful than one that lacks the desire or system mastery to do so, and even a party largely blind to such imbalances can still blunder into particularly OP or worthless options relative to a given challenge....