I think this is true in the short-term, but smart politicos watch the local media, especially if it starts getting reflected in letters from constituents. Tip O'Neill was the opposite of Max's view of politicians relationship with elite policy makers-- he would thumb his nose at them, but was intensely tuned to shifts in local opinion. This was one reason he was the first top Democratic leader to come out publicly against the war, since he began to see not just Harvard professors but working class constituents complaining about the war.
Some politicians forget O'Neill's slogan that "all politics is local" but a lot of them don't, especially if they see serious shifts in opinion coming from the grassroots. And those who don't are setup for primary challenges that can take them out.
Unlike Doug, I don't see our fractured system as necessarily anti-progressive-- it prevents easy national discourse on reform but it also prevents similar centralization to rollback past reform successes. It means leftists have to slog through the details of day-to-day politics to win, which I admit most of the left is currently unwilling to do, preferring to bemoan inevitable corruption. But that is a current problem, which past iterations of the left were not infected with and were therefore often quite successful.
-- Nathan Newman