It would probably/possibly work without them but the issue with folding kayaks on the sea or rivers is more impacts, there's a lot of rocks in the fun rivers and in the ocean/sea there's reefs and other abrasives.
Whereas with a rotomolded kayak its durable enough to even be used for rentals in those conditions. You pretty much don't have to give a shit with a rotomold since they can take a lot of abuse.