The question of blame is not one I will go into. But because you have asked about why one group blames another, I will simply describe the reasoning used by those who blame Palestinians for the start of the Arab-Israeli conflict, specifically those arguments relating to the UN Partition Plan.

The UN Partition Plan was proposed by the UN Special Committee on Palestine (known as UNSCOP). This committee was made up of 11 "neutral" countries (i.e. not superpowers):

• Australia

• Canada

• Czechoslovakia

• Guatemala

• India

• Iran

• Netherlands

• Peru

• Sweden

• Uruguay

• Yugoslavia

The members of this committee were tasked with traveling to and investigating the dispute between Jews and Arabs, both of whom wanted a state in the area, and were told to come up with proposals for solving the conflict. This was necessary because the British had essentially given up on solving the conflict, and had announced that the Mandate they were given by the League of Nations would expire and they would withdraw in 1948.

UNSCOP arrived, and met with Zionist leaders, who made an effort to work with them and showcase Jewish accomplishments. By contrast, the Palestinian Arab Higher Committee officially boycotted UNSCOP, arguing that it had no legitimacy and saying they opposed any partition. This is one reason why some blame Palestinians for the failure of the partition plan. While the Arab Higher Committee did secretly send representatives to meet with UNSCOP, the reception they received was chilly from Palestinian Arab locals as well. Thus the UNSCOP members noted that their interactions with the Jewish community showed them to be, "a state in the making", while they had less interaction with Palestinian Arabs. The Iranian representative even (and excuse my language, but this is a quote) said, "What asses these Arabs are. The country is so beautiful and, if it were given to the Jews, it could be developed and turned into Europe." UNSCOP did also meet with other Arab leaders, who were far less chilly, but were quite determined to make a forceful case (most of the time, Jordan was a notable exception, and Lebanese Christians had their own opinions). The Arab League's representatives called to expel Jews "illegally in Palestine" and said that those without citizenship there would have to be resolved somehow in the future, and the Iraqi FM compared Zionists to Nazis. Nevertheless, the Palestinian Arabs were unwilling to accept the legitimacy of UNSCOP, and believed it would be too biased against them, which effectively prevented any hopes that they would work openly with it and participate in its process.

The next part comes following the submission of the UNSCOP majority report (supported by 8 states). This report was put forward to an Ad Hoc Committee at the UN, which gave out tasks to two subcommittees. The first was meant to draw up a detailed plan based on the partition plan put forward by UNSCOP, and the second was tasked with laying out alternatives to partition. The second committee, largely run by Arab states, was obviously quite opposed to any partition, and argued it would be calamitous. Here, the Palestinians have less responsibility (the argument goes), but they were still lobbying against any partition or anything less than a single, Arab-run state.

The third juncture is following the passage of the UN Partition Plan in the UN General Assembly. The passage of UNGA Resolution 181 by more than 2/3 of UNGA members was celebrated by Jewish leaders, and recommended the creation of a Jewish state and an Arab one. The Arab leadership opposed it vigorously, and argued against partition, as did Palestinians. The refusal by Palestinians to accept the partition plan is often pointed to as another reason why they are blamed for the start of the conflict. The Partition Plan was solely a recommendation to the UN Security Council, which would have had to implement it for it to go anywhere. As you've noted, the plan was never enforced, and that leads to the fourth point of blame here that is given to the Palestinians by those making the arguments (the third being rejection of the partition plan). The fourth point is that following its passage, an attack was carried out on a bus carrying Jews by an Arab militia, which some historians point to as the "starting gun" of the violence that began the 1947 civil war. Not many people know this, but Jews and Palestinian Arabs had been at war for over 6 months (though Arab states covertly contributed) in the area, starting the day after UNGA Resolution 181 was passed, and up until May 15, 1948, when Israel declared independence and was invaded by most surrounding Arab states. This civil war is often pinned on the Palestinians, though less so since it was more of a "cycle of violence", and it's hard to say that the bus attack alone was what truly began it.

Hopefully that provides you with an answer to what you're looking for. I hope you consider using commiespaceinvader's suggestion in the future to get a more broad answer that goes beyond one side or another's argument to try and understand both sides' points of view.

I approved this question for now but in order to get an answer, I would recommend resubmitting it with a different wording. As it stands now, it's very difficult to answer since the "Why do some people ..." format is incredibly difficult. I'd recommend asking "What were the reasons behind the Palestinian boycott of the UN partition plan for Palestine? What was the impact of that boycott on what would become the Arab-Israeli conflict?".

Thank you!