if a political party wants a group of people’s votes, they should court those people. If they fail to do so, and those people choose not to vote for them, the political party only has itself to blame
You seem to understand this, yet apparently cannot accept that you are not the only group that the party wants (read: needs) to court.
As shitty as it is, the Israel lobby has a stranglehold on politics in the US. Both major parties are beholden to them, and need to bend over backwards to try to keep these groups happy, otherwise their campaign is dead in the water. That is facts.
The reality is, in this case, those two groups are mutually exclusive. You cannot appease both (you will just end up alienating them all). One of those groups is much larger and far more influential than the other, and has the power and will to destroy your chances of winning.
They courted the second group because its literally the only possible way they can win.
Despite what lemmy might have you believe, leftist thought is not the default in most of the US.
Become big enough and influential enough that you need to be courted, otherwise they have no reason to give a shit what you think.