Why do people say males stop growing taller by 16-17 while all the growth charts shows that an average 16-year-old male has another 1-2 inches to grow until 20?

As you l Point out they are no biased by the facts.

Males plateau in their growth at around 16-17 due to their growth plates closing at the end of puberty. If you notice, on the growth chart a male at the 50th percentile most of his life will measure 68.25 inches at 16years of age. That same male at 20 will measure 69.5 inches. The problem with the chart is that this plateau occurs more quickly in many boys. It is difficult to precisely estimate.