I'm not convinced it would have been the winning strategy in the election that you think it would have been, since there are a lot of voters in the US who are perfectly comfortable with killing Palestinians because they don't really understand what the nature of the conflict is, and would see any arms embargo as betrayal of Israel in their time of need after suffering a horrific attack.

This is not the case when you look at months of polling. It's a net gain of +6 points overall. If you look at just the swing states and see the margin of votes Harris needed to win, the votes from uncommitted in the primaries would have been enough to overcome that gap. Even more so when you recognize that there are over twice as many voters in the general when compared to the primaries. If you think that there is evidence that her changing position would be a net negative, back it up with evidence. Because all the evidence points to the opposite.

I can also apportion some blame to the voters who doomed Palestine

The US administration has been doomed Palestine, without any chance from the Democratic Party, it would have been doomed regardless. The support for the genocide is bipartisan, as evidence of Israel failing to meet the aid required put forth by the US for the last 30 days and resulting in zero policy changes.

I'm definitely blaming the people who organized the "uncommitted" movement

And what does all this blame accomplish exactly? Nothing but further division by blaming minority groups for daring to advocate for representation. Those votes were completely up for grabs. The campaign decided to ignore them.

It's not a game

Tell that to the Democratic Party. How can you say they actually cared about winning when they ignored so many voters in critical swing states and ignored the needs of working class Americans? It certainly doesn't seem like the realized how important this election was and acted accordingly to win by any means possible.

If I have cancer, and the doctor tells me about a treatment but isn't persuasive enough about it, and I ignore them, and now I'm going to die, is that the doctor's fault?

The issue is that neither offered any treatment. One offered again the current 'treatment' that has done nothing to help your cancer, the other said that 'treatment' is bullshit and said try this snake oil instead. People are stupid, many said fuck either option, and some went for the oil not realizing it was venom. If the doctor recommended a change to a genuine treatment and warned about the dangers of the venom, it would be a very different story.

You're holding Kamala responsible for three decades of Democrats ignoring the working class

I'm holding her responsible for her campaigning and her policies. I'm holding the entire Democratic Party responsible for the continuation of neoliberalism in the face of an existential crisis where left-wing populism was the obvious solution. I'm holding both the Democratic and Republican Party responsible for being beholden to the business class, racheting the country towards Fascism.