It is discussed though, people write articles about it and very recently more evidence seems to support it. The sweet potato could also be supporting evidence for some contact.
I suppose the fact that "native americans" were also from Siberia/Asia makes it complicated to separate Polynesian/Asian DNA from "native american" DNA.
The Mapuche people look stunningly Polynesian/Asian: https://en.wikipedia.org/wiki/Mapuche