As always, cool article. I love The Hard Problem. And, as always, I disagree with a whole bunch of stuff! So, let's get to it.
I would definitely argue that Zynga Poker does NOT constitute important proximal concurrency. Even if my chances of winning a prize are affected by 200,000 people, the way I play the game does not. The only thing which can change the way I play are the 7 other people at the table. I think there were 8 people in a game of poker, anyway. But the point remains - they don't affect my game experience just like everyone in eBay does not affect my auctioneering/bargain hunting experience. Only those people -interacting- with me do. Not just "affecting".
This is one thing that seriously bugs me about most Massively Multiplayer Online Games. Especially the RPG ones. There's so little proximal concurrency, and it's usually more of a pain for me to go find people to hang out with rather than just go solo. It's why I prefer team-based games like Team Fortress to a team-if-you-like system like Champions or World of Warcraft.
In something like TF2, what I do now is directly impacted by my teammates. I'll have to heal to help with this assault. Or go Spy to take out that rogue sniper behind us, because all our Heavies are dying. Or whatever. World of Warcraft's 5-/10-/25-/40-man instances are better than most of the game, because you're directly working with a team, but I find that until you hit 80, those are pretty uncommon occurances. I know Champions didn't even try to make use of them at lower levels.
As you start increasing proximal concurrency, the impact each player can possibly have is lessened. Spritzey just pointed it out, talking about Fearzone's game idea: What's the point in playing if you don't make a difference? If you spend all day trying to get this hard-to-capture point, and finally get it, but overnight a thousand enemy players carve a bloody red hole through your bright blue nation? There has to be a game which you can have fun in with that huge overarching goal only sitting behind it, not just a game where you work on a goal. Players would rather feel important than insignificant, and so game design has followed. Excepting technical limitations, I think that's the main reason games tend to work more on the basis of low proximal concurrency, with potential non-immediate bonusses if high server concurrency happens.
With regards to "temporal" proximal concurrency, I'm not really clear on how it's important at all. I mean, I could just go and play Space Invaders or something, and post a score to the leaderboard. Are you trying to tell me that my competition with every other player playing the game is important? Because I can't see how it is, at all. Their actions don't affect me, except possibly to egg me on to get a higher score and waste more of my life competing against people who don't have one to waste.
Finally, what's the point of increasing proximal concurrency? How does it make the game any better to play? Let's take MAG as an example, since lots of people like it. Even if we're only talking 64p games. Does having 32 enemies really make the game more interesting than having 16, or 12? You're more likely to be sniped from some obscure location. You're more likely to have your kills stolen by your own, larger team. There will be more spamming of ranged attacks. I'm mostly speaking from my experiences with Team Fortress 2, here, which goes from very small 3v3 games up to about 16v16. And those last, the 32p servers, are just unbearable for me. So I don't get it - what's the appeal, here? I understand the MMORPG thing, where you can hang out with heaps of people, you can play cooperatively with people, but player versus player with huuuuuuge teams is just no fun at all.
So, tl;dr:
-Temporal concurrency doesn't mean much.
-Players like to feel important rather than insignificant, so increasing concurrency (in any way) isn't necessarily good.
-Most so-called "Massively" Multiplayer Online RPG's tend to not do much with immediate proximal concurrency.
-Why are we trying to increase proximal concurrency again? I hate kill-stealers and ninja-looters!
Thanks for the discussion, everyone, and to John for writing the article.