Because in practice, isn't this a bit like "Kleenex" - where everyone knows you mean "tissue" (EMCAScript).
Oracle is an incredibly litigious company. Their awful reputation in this respect means that the JS ecosystem can never be sure they won't swoop in and attempt to demand rent someday. This is made worse by the army of lawyers they employ; even if they're completely in the wrong, whatever project they go after probably won't be able to afford a defense.