To start off, this is not about parents going afk because their children set the house on fire. I don't like it, but that's not what is killing WoW.
Instead I refer to the parents themselves. Let's start with some facts:
Fact one: Parents are lame by definition.
Fact two: Parents do lame activities.
Fact three: Parents have children, again, definition.
These lead to the inevitable chain of inevitable killing of WoW. What parents do is lame and they play WoW, so therefore WoW is lame. They have children and they pass this lameness on. Every parent who plays WoW is another set of children who will not play.
Now that I think about it, maybe that's a good thing.
Dear Parents, please play WoW so your immature children don't.
P.S. Dear Parents, please raise good children.