Polling had its heyday when they had enough technology to make it work but most people still used landlines. The tech is even better but it is less reliable since more people are off the landlines.
People think that pollsters are trying to accurately determine the sense of the voting public, but that’s incorrect. Most of these pollsters were trying to INFLUENCE the voting public. All rules of probability and statistics can go out the window when the pollster is manipulating the results to support a predetermined outcome, as I’ve posted endlessly about. The poll results showing Hillary in the lead were intentional, nothing to do with landlines or anything else.