> (Fun question with not-so-fun answers: why isn't the filibuster gone already?)

Because both parties are scared eventually the other party will be back in the majority.

Because I don't think it's vestigial, I think it's serving an important function of governance that never made it into the official rules but is nonetheless necessary as a stabilizing effect. It doesn't have to be the filibuster but something ought to provide the effect. It should be easier to block legislation than to pass it. It wouldn't be a good thing if you could have huge policy swings when a 51-49 becomes 49-51. Being able to, with effort, demand specific pieces of legislation reach a higher bar biases us toward the status quo.

RCV / Ranked Pairs of course. The IRV decision process is still a relic of the two party system, with the possibility for some pretty terrible strategic-voting dynamics as votes diverge from just two major parties.

> Certain politicans know this and have made RCV illegal in their state.

That would be Republicans.

While Democrats have pushed across multiple states for changing voting mechanisms, Republicans in eleven states have pre-emptively banned any and all use of RCV at any level within the state.

Score voting (or STAR) is better.

Not important but Mamdani would’ve won without ranked choice voting too, it didn’t play a role in the end.

Obamacare was passed via regular order (60 Senate votes), not reconciliation. There was a follow-up package to tweak it that passed via reconciliation in 2010, but the original bill was regular order. It's the only (very brief) window where one party has held 60 Senate seats since 1977.