All I have to say is, yes.. I crate Fred for my
personal piece of mind when I am not home. Although, he does not stay in his crate for more than 10-18 hours a day like that excerpt on the website suggested.. I crate Fred a total of about 2-3 hours a day when I am gone. I do not want to give him free roam of the house because I do not want him to get curious and eat things he's not supposed to be eating or biting things that are deemed bad for his health (wires, cords, cable lines, wooden chairs) or even jumping onto things and falling off. Somewhere along the lines of keeping him in his crate when everyone is gone, he has grown comfortable with his crate like it was his little refuge spot when he wants to nap, or lay around. I did not train him to feel comfortable in his crate (if that's even possible!

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As for the comparison between child and dog, I do not understand. You train a dog, you teach a child. The life of a child is so much more complex than that of a dog. Children have to learn things that, of course, a dog will never understand such as morality, dealing with choices and bad decisions, table manners, et cetera. I am not saying that I do not treat my dog like my own child, but in terms of "treating him like a child".. I give him my love and affection. I spoil him and I pamper him but it is near impossible to raise my dog like my own child.
"So, to me, leaving a 2 year old dog in a cage while you go to work is like leaving your teenage son in a playpen." A two year old dog was born crawling on all fours and stays on all fours throughout his/her life. A teenager was born, crawled on all fours and then learned to walk on two feet. Let me see your dog walk on two feet, and maybe than will I begin to understand this analogy. You put your baby in a playpen when doing house chores because you try to keep them from harm. You keep your dog in a crate when you're gone for the same reason. The difference is, you don't leave a baby unattended in their playpen when you are not home. Babies are not banned from grocery stores and highly populated areas. Dogs are (in Texas atleast).
If I had the choice to leave my little man in a crate when I'm gone or take him with me without leaving him in the car, I'd take him with me. But, there are places with rules and restrictions that I cannot change therefore I have to keep him in his crate when I am gone.
I think it's just all personal preference. I don't see anything wrong with it, and sometimes I even think Fred loves his crate!