Today's Frustration re: DC Statehood

In the constitution the federal District, later called the District of Columbia was marked at 10 miles per side which makes a total of 100 square miles. 31 of those square miles went back to Virginia in 1846 and became Arlington County. This leaves us a total of 69 square miles.

So why is someone at YouTube saying that DC doesn't deserve statehood and needs to be "put back" to the 10 square miles it's supposed to have? Is innumeracy that rampant?