Political Memes

The issue is that any third parties are so weak as to be non-existent. Limited voting helps the right wing more than it does the left, so voting third party only hurts the Dems. There's a reason the GOP is trying to make it harder to vote.

Sadly, the Republicans are the strongest party - they are unified and fixated on one goal: dismantle the US government and privatise everything for maximum profit. They are all on one message and move as a powerful group. Their organisation (and lack of consistent values) is what keeps them in power.

The Democrats love status quo so when they are in power they don't want to make sweeping change, however needed. They are also quick to gatekeep within their ranks (ousting Franken, for example, who was exceptionally good against the GOP). There's a much more varied pool of ideas and goals, so they are unfocussed and weaker because of it. They also have yet to realise the political playing field has changed in the past 50 years.

Independents like the Green Party fail to raise any numbers because they are even more wildly disparate in their goals and ideologies and never show an interest in local politics, where you actually build supporters and show you can be an effective leader. They only turn up for presidential elections and nobody knows who they are. After they lose, they disappear for four years. You can't build a credible party by starting at the very top.

Ranked choice voting would solve some of this, but that'll never happen.

TL;DR: the US is boned.