Democrat or Republican, why not just choose independent?

You don’t vote for a party. You vote for the policies, principles, and people you believe will do the best job. Person over party would go a long way in keeping assholes out of office

Vote against the worst party. Don't throw your vote away on some independent hoax.

Because Democrat, Republican, Independent, Green, etc are not on the ballot. Only people who may or may not have got funding by a political party are your choices.

As much as I wish there was a party that truly represented progressive grass-root and peaceful views, there's not much national motivation to branch off from Democrat and Republican parties because that would pretty much split the vote and give the other party an easy victory (Election of 1860's a good historical example - Lincoln's victory was an electoral landslide).

Because of how bitterly polarized American society is today, a risk such as making any effort to, not only amass a following but also emerge between the two largest and oldest current parties, is something someone would not like to take especially if their identity is embedded within politics.

Voting for independent will likely be the same as not voting at all, but I'm not the one trying to tell you which party to vote for (or not vote for in that matter).