Problem is that this project is by an extremist group. It's easy to agree on things if you think everything is on the table.

Second part is that the Republican party tends to focus on making sure that people are not educated about what any of the things they talk about mean for the people in the party. Instead they focus on creating the idea that they are under attack by some phantom enemies, going so far as using totally insane conspiracy theories and such and focus on how their policies will hurt those enemies that are the cause of all their current problems. And once people think they're being attacked, they'll give up anything to retaliate.

Then looking at the Democrats, you have a party for right-wing moderates. This party has very little appeal to anyone since most of the right-wing people in the country are enamoured by the extremists. So they don't really have anything they can do that would appease their target audience all that much. I mean moderate conservatives basically want everything to stay exactly the same.

And the left wing half of the country basically has no party creating policy for them at all, and due to the electoral college and various other systems in place, there's no room for more than two parties, and it's extremely rare for a party to disband so that another can do much of anything.