Nowhere did I say that SG were not influential or popular. I simply stated that I don't like them. Peter, Paul, and Mary were quite influential and popular, but they're not very good.
I have no "negative stigma about covers." There are plenty of artists who improved on another person's original song, and I never stated otherwise. In the case of Watchtower, though, I don't think anyone (Dylan himself included) ever topped the version on John Wesley Harding.