Polls were fairly accurate last time given the margin of error. Combine that with the fact that they have improved since then (evidenced by their much greater success in 2018, especially in the House elections/popular vote) and the fact that many of the final polls took place right as the Comey effect was being felt, and Trump’s approval rating has remained consistently dismal... There is certainly no rational reason to discount them.
Polls were accurate nationally in 2016 within the MOE, not at the state level. Polls had Republicans inflated in Nevada, where Hispanics are routinely under represented going back to 2010. And likewise in several election cycles, Republicans have been underestimated in the Midwest going back to 2010. Even in 2018, Republicans held OH and IA Governorships, in spite of the polling and did much better than expected in Wisconsin Gov and MI Senate. In Indiana, Rasmussen and Fox News had Donnelly ahead of Braun and Braun won. Ohio Senate was also much closer than the polling averages suggested by as much as 6 or 7 points.
