I think Bill Nye is right in that the average male doesn't know how to tie a necktie anymore. It is a fashion of the old times and the art and knowledge that has always passed generations to generations is being lost to other customs that the average male learns instead of tying a necktie.
It's most likelier than not that most men do not know how to tie a knot, despite it being a useful skill. I would go as far as to say that those who do have a military, navy or boy scout's background. This a rather unfortunate aspect of modern day society.
Most guys don't know how to tie a necktie unless a dad, uncle, grandfather, older brother etc showed them how. There are tons of clip on and zip on ties available in stores even for adults. It's a skill and something that needs to be taught. Good for Bill Nye for breaking it down.
I think the most Americans will agree that many of our business situations have become out of the norm, and have turned to a business casual affair. Properly tie a necktie is a task that is nto used that often as business casual has become in the forefront, but for those who need to learn, they just turn to You Tube to learn how to tie a tie!