It wasn't palms, it was toromiro.
The real deal were in the Paschalococos palms.
As I suspected those were included in the tribu Cocoseae so they were the most important plant in the island for humans.
When the palms went extinct in 1650 the society entered in a whirlwind extinction situation. Rapa nui inhabitants commit ecological suicide to themselves and the rats and foreigners carrying diseases give them the final blow. If you replace Paschalococos with Sophora there is a hidden big collateral effect. Even if the island is still covered in luscious green is not the same family of green.