My friends are greedy, selfish bastards, it turns out.
I learned this from Zynga's newest golden turd of a game: Empires & Allies. How did I find out? Metal. Most of the resources in this game you generate in bulk for yourself. Everyone seems to have twenty lumber mills, twenty farms, and twenty oil wells. Metal, on the other hand, comes in 5 varieties, but you can only create one of these (the lowliest, copper) for yourself. The others must be obtained from your friends. Each of your friends (determined at random, as far as I can tell) can provide a different one of these metals including the worthless copper (that's a design mistake: none of them should give you copper). When you visit that friend, you can collect that metal from them, but only if they have a mine that's finished producing it. That, however, is a big problem. You friend's mines aren't producing anything most of the time, because for them, the mine only makes worthless copper. For you, it's precious iron, uranium, gold, or aluminum, but for them, it's just copper. They need to come to your mine for uranium. See the problem? Nobody builds mines, and even fewer players activate them and keep them stocked with fresh, unharvested copper.
I figured all of this out, so I decided I would help my friends by keeping my mines running. I picked the shortest cycle of copper so that it would be ready fast, and my friends could come by and harvest the real metals that they need. And they did. I accepted their help, often from 4 friends at once, and watched their little icons hit all 5 of my mines, never bothering with anything else. Why should they? They can make all the wood and oil and coins they need. So instead of getting help from 4 friends, I'm really only getting help from one... and it's not help that I want. I get only copper.
Very few of my friends keep their mines running. I'm thankful for those that do, it's good to have friends you can count on. The rest of you, feh! I've got your number now. I know you only come visit me for the iron I provide. You take and take but none of you takers keep your own mines running. I know you know how it works, because you only hit my mines, and you hit them every time you can. Yet not one of your mines is running. Some of you don't even have any mines at all! Zynga has brought out the worst in you.
There are other ways to get the metals, but they are unpredictable and insufficient. Combat gives you some, but you lose almost as much in destroyed units as you gain. You can also buy the metals for coins, but the cost is prohibitive - I was buying what I could afford, but I needed much more.
My friends are all really nice, cool people. It just makes for a good read to claim they're jerks due to their behavior in a game. Sorry friends!
This metal mechanic isn't what caused me to quite E&A. It was a combination of general boredom and the "you must have friends gift you a metric ton of crap in order to get upgrades" mechanic they added a week or two ago. I despise that mechanic, and won't play any games that use it.
Empires & Allies is a much better, more interesting game than any of their others. Even so, it's a pretty shallow clickfest with only the thinnest layer of strategic options stretched over it. It was mildly amusing for a couple of weeks, but it's not 1/10th the game Advance Wars is. My poor friends at Zynga, trapped by all those piles of cash. Forced to make only small improvements to dull casino-addiction style games. At least they're eating well.