If you watch know that the swamp is filled with people just like this who got Carter, Reagan, Bush I, Clinton, Bush II and Obama elected as well, then this is a useful documentary.
Unfortunately the implication by the documentary makers (several of whom have direct connections to the DNC, including producers who are DNC activists) is that Stone is some kind of outlier. Nothing could be further from the truth. But the makers are themselves part of the same swamp so they are going to imply this is a phenomena solely of the other side. Only a moron would believe that.