Once upon a time, representatives were responsible to their constituents, and their constituents lived in regions with very different economies and traditions. Now representatives are much more representative of their parties and their party’s donors and ideologues. There’s still a big urban-rural split, but in most districts representatives are guided by the party ideology and not by the wishes, needs, and demands of their constituents.
In the old days, local interests and sentiments weakened the power of parties. Today, those in politics are partisans first and foremost, and those who aren’t are more responsive to Washington DC attitudes than to what their constituents want.
The Framers’ Senate of the States countered the influence of popular parties.