I think people often forget or do not know the origins of the breed.
The Yorkshire Terrier was developed near the township of Yorkshire, England, on the British Islands. Prior to their becoming house pets, they were used as ratters in the coal mines and mills of the area. During this time the average Yorkshire Terrier weighed around 15 pounds, (about twice the body weight of today's Yorkie).
Yorkies larger than 7 pounds really isn't unusual being that the larger size is still in the gene pool.
My Little Man weighed just under 10 pounds a couple weeks ago at age 2. His Mom is 6 pounds and his Dad just under 4 pounds.
Below is a pic of him.