"You say this '2-1-2' thing is good?  Okay, let's try it!"

I really hate this meta.  Thankfully, normal 5v5 queues seem to have enough jungle mains to ignore the sheer power of the quad-Targon strategy, but arranged 5v5 is a different story.  And the gold, Jesus the gold.  I don't think the strategy is that good, but there is money there, and Riot's nerfs are going to be 100% necessary.  Let's talk for a bit about why:

Money

I'm going to just rattle off some numbers here (a friend did the math, and I trust him; if you can find different numbers let me know): Right now Ancient Coin and gold generation Quints generate comparable gold to afk-jungle farming for the first ten minutes of the game, after which, jungle farming would logically begin to outpace the passive gold gain from support swag.  On the one hand, this doesn't take the new jungler itemization into account.  On the other, this is just Ancient Coin, the weakest gold generation item in its weakest form.  Hell, just upgrading it to Nomad's Medallion will about double the gold it gives you.

So then let's look at Relic Shield, which gives you about 60% more gold than Ancient coin (40 gpm).  But if you're in a lane with double Relic Shield (justifiable on a marksman for sustain, justifiable on a bruiser for the HP and CDR), this more than doubles up to 90 gpm, which is almost four times the gold you get from an Ancient Coin.  This means that, all else equal, double Targon is giving your "jungler" a lot more gold than he could get just by farming the jungle.

Sounds like a good deal.  What's wrong with that?  The short answer is not much, and that's precisely the problem.  The long answer is that running a 2-1-2 lane composition gives two people on your team a bunch of gold and sustain while robbing them of experience, which, unfortunately, often ends up being worth it.  I keep saying that this is a problem, so I think I should probably get to the "why" of it:

Counterplay

Think about the implications of not having a jungler.  Well, there are suddenly a bunch of free resources in the jungle...that's cool, and it suddenly makes map control a hell of a lot more important (you don't have a jungler doing it for you anymore).  This means more snowballing, but it's more of a social problem than a mechanical one.  This makes map control more important because now it's suddenly no one's job to control your jungle for you.  Accordingly, control of the enemy's jungle will fall much more easily to the team that's ahead.  This has potential to be frustrating, but even that doesn't hold a candle to the big problem of not having a jungler: Lane matchups matter.  Like, a lot.

As a top laner, I've had my share of experiences being put in a losing lane.  Ever want to have a bad time?  Try laning Wukong against Darius.  You'll want to break something after.  But with a jungler, you might be able to get through the experience with enough momentum to make a difference in the midgame, despite the early unpleasantness.  No jungler, and you get matched up against a lane that outranges you, out-aggros you, or just mechanically screws you over?  You're done.  Unless you are a lot better than your opponents, you are going to lose your tower, feed a couple of kills, and leave lane three to four levels below your opponents.  Then you will probably lose.  Junglers were a healthy thing for the game, and while 2-1-2 is probably a good thing to keep viable for the occasional strategic surprise in a competitive environment, it should NEVER be the default.  That's why Targon is getting nerfed, and that's why this meta will be unhealthy for the game if it continues.  

Agree, disagree, let me know what you think.  We can have a discussion :).  But I, for one, am glad to see this go.