I think McGovern had a lasting, profound, political impact.
He was the first national candidate to establish the democrat party as the party of deadbeats, misfits, losers, socialists, hippies, yippies, potheads, and queers.
Before McGovern, democrats like FDR, Truman, Kennedy, LBJ, Humphrey, etc., were mainstream, normal, civilized people, albeit wrongheaded.
Beginning with McGovern, the democrat party has pandered almost exclusively to the weirdo dregs of society.