Why don't hundreds of surnames depend on rankings?

There are only 56,800 surnames.

There are 693 1 single surname, 4,329 double surnames, 65,438 three-character surnames +06 15 four-character surnames, 569 five-character surnames, 22 six-character surnames, 7 seven-character surnames, 3 eight-character surnames and 7 nine-character surnames in China.

How can there be so many!