The off and on again limits aim to prevent exploitation without impacting normal players.
Blizzard has always had a strong stance against anyone trying to exploit game mechanics or bugs for gain in games like StarCraft or WoW. When real-world money is involved, as the auction house in Diablo III introduced last month, such security is paramount. That's why the company from Irvine placed restrictions on the number of games a player could make in a given timeframe. Unfortunately, legitimate players complained about the restrictions and Blizzard lifted them. Now, the number of game instances you can create in Diablo III will be limited once again, but hopefully the variables have been tweaked enough to ensure real players are not affected.
Vaeflare said Blizzard would continue to ban accounts with suspicious activity, but this limit would be an always-on security measure. "While we regularly take action against accounts for the use of unauthorized third-party programs and bots, this additional measure will help us further preserve and protect the integrity of the game and economy in between ban waves," he said.
Blizzard has struggled with making sure Diablo III stays as free of exploits as possible while not pissing off players. At one point, you couldn't play past a certain level in a certain timeframe with a digital copy, but Blizzard lifted that after a week. And of course, the whole always-connected-to-the-internet thing is just another restriction on play meant to facilitate multiplayer, but also allow them to keep an eye on players.
The change to restrict multiple game creation in Diablo III is not yet live, but soon you will not be able to spam the opening of games every three seconds. Also, if your cat rolls on your keyboard while you nip off to grab a cup of tea, you may end up getting banned from accessing the Diablo III servers. If that happens, you can email Blizzard with a cute cat picture, and you may get off scot free.