How Absurd Is A 40 Yard Dash Time?

There are so many other variables involved in football speed versus a straight line 40 yard dash time (in shorts and a T-shirt) that its ridiculous to use 2/10's of a second to demonstarte the 2 foot separation 20 yards downfield.
Its apples and oranges.
CB/WR races begin 5 yards downfield, from a moving start.