Maybe, maybe not. Easter island is one of the most isolated islands in the world and is also one of the easternmost islands in the Pacific. It's still a long way to go to get to South America from there. Maybe a few family units arrived and then forgot about boat building and navigation for a few generations because the islands land resources were so plentiful. I think something similar happened to native people on Tasmania - they took a boat to get there, but forgot how to build boats eventually and so were stuck on their island without the ability to go to mainland Australia.