So the birther stuff was started by the Hillary supporters. Whether or not Hillary herself was involved can't be known for sure, but we do not it was her supporters who started it.
Nobody ever claimed Trump started the nonsense. To say he didn't is a strawman argument.
What people have said is that Trump used his brand to promote the nonsense for years.
And he only put it to bed this week, but not really. None of the racists that still believe Obama was not born in the US take his statement seriously. They don't care if the person they support lies to others.
That's what people don't understand.
Trump supporters do not care about silly things like the truth.
They do not care about things like equal protection under the law. They want to hurt some people of color. Be it Mexicans digging ditches or Muslim children fleeing a war zone.