Established entities like a party or elected politician get lazy and sloppy and learn how to blindly compromise once they get in power
Getting in power is seen as the END result rather than just the start of political action
When blindly following a party, you HAVE to live by the creed...
We are against ideological arrogance! Sure, it is OK to think that you are right on an issue and your opponent is wrong, but when an entire party exists, there are bound to be some mistakes of the collective party! And also, it is ridiculous to say that an entire party is 100% wrong (or right) about everything!
There is a VERY old premise that people that have a common agenda must get together to combine their resources to be more effective. That's when the cheesy politics start. George Washington warned us not to break into political parties! Internal party fighting is like a rope with a knot, which means that it weakens ITSELF by 50%.
So-called "party loyalty" is another atrocity! There are scenarios where a candidate is the frontrunner or even the assumed nominee months or years before the primaries and caucuses and voters are somehow conditioned to vote for him! Another scenario is where you know the guy is slime but you keep supporting him (like the Democrats did for Bill Clinton) because he is in your party!