Sanders won in polls vs Trump. Clinton lost. The party just decided they'd rather Trump be president than Sanders.

Ranked choice would absolutely still help. The two party state is utterly awful.

Depends which form of ranked choice. The naïvely-designed ones like Supplementary Vote, Contingent Vote, Instant-Runoff Voting, Top Four, Final Five, etc. don't fix the two-party system at all, since they only count first-choice rankings in each round, just like our current system. Unfortunately those are the only ones being advocated in the US. We need Condorcet-compliant systems if we actually want to fix the spoiler effect and end the two-party system. Total Vote Runoff/Baldwin, Ranked Robin, Schulze, etc.

As an aside, ranked voting isn’t what I’d consider ideal for the general election, either. It’s still heavily disproportionate. Proportional voting is far superior for ensuring representation.

Yes!

Any form of single winner ballot (ranked choice or FPTP) is gonna favour the centrist, even though that means 50% of the population don’t get their ideal representation.

Actually, both FPTP and RCV suffer from the "center-squeeze effect", so centrist candidates are at a disadvantage and they favor more polarizing candidates.

As an Alaskan voter, ranked choice is the only reason we have a female, Native American, Democrat congressional representative instead of Sarah Palin filling Don Young’s deep red legacy.

Peltola would have won under FPTP, too; RCV didn't change the outcome. The real issue is that there were two Republicans on the same ballot vs one Democrat, splitting the vote with each other.

RCV is equitable and works, but not in the way progressives hope. It allows for the most centrist candidate to be chosen that appeals to the most possible people.

No, it suffers from the center-squeeze effect and is biased against the candidates that appeal to the most possible people. In Alaska's special election, for instance, Begich was preferred over both other candidates by a majority of voters, but RCV incorrectly eliminated him first. This flaw gave an unfair advantage to progressives in that election, which you may like, but it could just as easily give an unfair advantage to conservatives in a future election, which you wouldn't. (If there are two Democrats and one Republicans the ballot, for instance.)

In my opinion, for single-winner elections, we need better voting systems that do always elect the candidate who appeals to the most possible people, which will allow third parties and independents to become viable, which will open people's minds beyond the two-party false dichotomy.

A two party system just becomes a battle of political extremes. And like it or not, being progressive is far left for a reason, especially in America. And I consider myself fairly progressive leaning.

Yes, and RCV perpetuates that polarization because of the center-squeeze effect.