Along these lines, policy kind of went to shit when they got rid of earmarks.
It used to be some congressman from rural Ohio being able to vote in favor of union stuff his people want but the party doesn't because he knows the bill has some pork for his district to make his people happy so he'll be secure next election.
Now that guy's security next election is all dependent on party funding so he's gotta vote the party line every time and any deviations from the party line are a complex game of favor trading and backroom dealing and whatnot.