This is why nobody takes economists seriously. What you lose in simplifying down to this model is literally everything. The coconut economy has zero predictive power.
In the real world, distribution effects dramatically affect the functioning of the economy, because workers are also consumers and owners of capital are siphoning off the purchasing power of their customers. Productivity isn’t the question in the modern economy - we’re already massively overproducing just about everything - our problem is both our wealth and production allocations are borderline suicidal.