I challenge this statement, based on research and experience. Boredom is certainly a huge problem with two-year-olds, but even if it were not a contributing factor, the twos would still be terrible. The terribleness comes from a developmental stage common to both people and dogs. The Scientist in the Crib and Super Puppy both discuss this. Little'uns go through a stage where the want nothing more than to please you. This is a primary learning stage--imitation. But that would only get them so far-right? You can't learn everything about the world by just doing what your parents/owners do. So, the question becomes, "what can I do that is not what my parents want me to do?" Eventually, the moment comes where that you'll suggest to a toddler that he/she spends some time doing the one thing in life they most enjoy doing--"Let's spend the afternoon eating ice cream!" They will think to themselves "she wants me to eat ice cream, and she doesn't want me to stick a wet screwdriver in the electical socket. Hmmm. I wonder what she'll do if I go with the screwdriver plan anyway."
Of course this thought is deep below the consciousness, way down in the primordial brain. It doesn't translate well to the conscious brain and seems to cause them as much stress as it does you. I think this may be presenting itself in David's decision-making abilities. We'll give him a choice, he'll decide, then change his mind, and then again. We have to set a boundary about many times he can do this (the boundary is generally, "ok, I'm annoyed"), but no matter which choice we finally settle on, he'll cry, wanting the other one. "I want yogurt, no, I want raisins, no, yogurt, raisins, aghghghgh!"
As I understand it, this is the case no matter how "entertained" the two-year old is. Eventually, they will want to do something you don't want just to shake it up.
Later, terrible fans.