Most hunters can't count off an accurate hundred yards without a tape or a laser range finder. Your account proves that those who said they shot a 160 probably shot a 140.The majority people that guess scores on the internet are just blindly guessing, but if you look at each point and estimate length and mass, it’s very possible to get close to a real score. It’s not a fast process (at least not for me).
My veterinarian sent me a picture of a buck a couple weeks ago that he killed and asked what I thought it scored, and I did the math and told him 148”. He texted me a few days ago, and his taxidermist scored it at 147 1/8”. He said people had guess it up to 160”, and I was the closest. He was happy, because he thought it was only about 130”.