Both left and right have fringes, where silly claims are made. Thus, for instance, after Fukushima some lefties went hunting for dead babies on the U.S. West Coast from ionizing radiation supposedly traveling across the Pacific. Like I said, fringes.
But the fringes aren’t very relevant—unless the inmates are running the asylum. That’s what you have today on the right, where Republicans and Tea Partiers overwhelmingly reject mainstream knowledge in key areas and these views are also endorsed by elected representatives and even presidential candidates.
Bingo. The wackaloons on the left aren’t in a position to decide on legislation.