He was repeatedly elected by his constituents and argued on behalf of their freedom. All Sharpton has been elected to what? And argues that the federal government should be a tool for looting one group of citizens for the benefit of another group of citizens. Your analogy is flawed and disengenuous. It relies on presenting a series of half truths. I know of the other half.
Sam was a professional rabble rouser. The post-Revolutionary rehabilitation of his reputation has been pretty successful. But it is still true that "after independence was declared his influence declined; the radical was replaced by more conservative leaders, who tended to look upon Adams as an irresponsible agitator." (from the americanrevolution.com website).
American Revolutionary leaders are not fungible; Adams was on the fringe. Now, fringe leaders serve a useful purpose in getting the ball rolling, there is no doubt. But they do get "replaced" as soon as gains have to be consolidated and actual working relationships established.