Does it mean "But few exporters could benefit from it"?
"Rarely mentioned among explanations for the above is the Aussie dollar: five years ago the strong currency was a bonanza for consumers who could buy cheap goods from overseas; a 25 percent depreciation since then has been a boon for exporters but few others. In addition, while a spike in commodity prices in the past 12 months sent corporate profits surging, almost none of that money has made its way to workers."
"...has been a boon for exporters but few others" means that it has been a boon for exporters, but NOT for everyone else, only a potential few. The phrase, "but few others," is in understated tone, and likely indicates that no one else at all will actually benefit, other than exporters. This would be logical, since a weaker Australian currency means that Australian goods are now cheaper in other currencies, relative to the Australian dollar. Importers of foreign(non-Australian) goods, for example, have to pay more Australian dollars to import those goods which were much cheaper when the Australian dollar was stronger.
"for exporters but (for) few others".
The omission of the preposition happens a lot in speech. For the sake of clarity, however, it does no harm to repeat the preposition, and this would be both grammatical and stylistically acceptable:
for exporters but for few others...
