I can vouch for that! My big guy, Yansa, is a purebred GSD, 31" and 130lbs. He's huge but is a total klutz. He's a rescue that is most likely from a BYB..... Dogs that are too large have power, but lack agility, and that is IMPORTANT to have.
No. It could easily be a BYB/Puppy Mill Dog....
and the pound puppy crew.