On Palestinian control of the narrative.
There is more layers of complexity than that too. Prior to the last, about, ten years, the Arab World and Iranian World were both quite pro-Palestinian, supporting them monetarily and, more importantly, diplomatically. If we rewind back to the 1970s, the entire Arab Oil Embargo was predicated on Arab support of Israel, and remember, it hit more than the US, it hit all of western Europe.
Now, bear in mind, the US has always been an oil producing state. Literally, the industry was invented in the US. Sure, in the 1970s it was a smaller industry than it had been and the Arab world dominated the supply chain, but the US still did (and does) produced oil. The Arab Oil embargo against the US didn't have the effect on the US that the Arabs wanted: reducing support for Israel, rather, it just made the US wake up to oil dependency and thus began the push for "energy independence" in the US and the expansion of the US Oil industry to the point where the US is one of the top oil producing nations in the world once again.
But you know where the embargo DID have the desired effect? Western Europe. After all, aside from the North Sea, Europe isn't exactly noted for its large oil reserves. The oil shock shook the European governments and caused them to... reconsider prior support for Israel they had shown. Further, bear in mind that anti-Semitism in Europe has always been a much more institutional and entrenched idea than it ever was in the US. So you have governments reorienting to be against Israel, and the European media following suit, plus the cultural anti-Semitism to play off of?
So a large contingent of media representatives reporting on Israel, especially those from Europe, were already giving cover to the Palestinians all the way back starting in the 1980s and throughout the 1990s. Now, have a few American reporters into the mix of the international press pool. They don't have institutional reasons to take sides in the conflict (due to the media in the US not answering to the government, unlike, say, the BBC...), but they now do have a SOCIAL reason to begin framing things that way. After all, all these elite European reporters are framing it that way, and they don't want to be ostracized from the elite reporter circles, and add in some good ol' fashioned American inferiority complex towards European establishments, especially among the petty-elite of the US (which the media class generally is a part of), and finally the "access" issues outlined above and, well, you have a recipe for the US mainstream media falling into line with the Palestinian narrative.