Probably because there are no ancient giants.
I mean, the idea that the Smithsonian is masterminding a conspiracy is absurd. They'd only gain from such a discovery. Why hide it?
Would they though ? Gain from such discoveries
The revealing of the fact that these Giants existed would completely change the History of America as is known , and written in the History books
Thats a tall , tall order , plus you have the explaining why this archaeology was not put out there from the begining in the first place
Tough spot the Simthsonian put themselves in
But here is this , in 1890-91 , read
Ten skeletons "of both sexes and of gigantic size" were taken from a mound
at Warren, Minnesota, 1883. (St. Paul Pioneer Press, May 23, 1883)
A skeleton 7 feet 6 inches long was found in a massive stone structure that
was likened to a temple chamber within a mound in Kanawha County, West
Virginia, in 1884. (American Antiquarian, v6, 1884 133f. Cyrus Thomas,
Report on Mound Explorations of the Bureau of Ethnology, 12th Annual Report,
Smithsonian Bureau of Ethnology, 1890-91).