I think that Second Life (still running, and where you can still trade in-game money for real money see: https://community.secondlife.com/t5/English-Knowledge-Base/B...) is a better example than Diablo 3
I think that supports my overall point though: This isn't new, and you don't need bitcoins to make it work.
Items also had a maximum price limit. This meant that items worth more than $250 USD at the time had to be sold for lesser value items, or for gold (which had the downfalls listed above).
The problems with Diablo III were the restrictions on the marketplace. Blizzard never allowed prices to hit their true equilibrium, and it created an off-site black market along with other inefficiencies.
There is no reason that a game economy should be ruined in one way or another by a real-money exchange rate. There are many games where players buy & sell in-game currency for real money, where the in-game currency holds a very steady real money value.
Take Runescape for example. One million Old School Runescape Gold has been worth roughly $1 USD for the past 6 months. The volume of in-game currency which has been bought and sold in that time period is in the tens of millions of USD.
Source: I run http://r2pleasent.com - a site that buys and sells in-game items.
Be called a noob because you use a whole free avatar or free avatar components.
Be instantly blocked by just about everyone you try to talk to
Be unable to access adult-rated sims and regions
Spend 4 hours attached to a dancing poseball that pays you L$1 an hour