Farmville and many other social games are designed to interact with people and reward them AS IF THEY WERE DRUGS. Thanks to the rewarding system on constantly giving you little things and keeping the BIG reward right in front of you, your brain releases chemicals to reinforce it. Then when you get the big thing (and rush of chemicals) they give you a new big thing (that you learn to crave as getting it will give you the happy brain state).
So keep in mind, to some people farmville is legitimately a drug (or rather manipulating brain chemicals to use drugs you already have).
I'm not excusing what she did, BUT it does give a more correct and better understanding of why is was done instead of saying "a stupid game"