I think poor contribute only to rich. They can get things done with low payment but sells then in other country with high price. Like clothes and shoes are made in poor country but look at their prices. Those country do all they can to keep people on poverty to use them.
It was part of a line of business pursued by poor people who were struggling to get rich. Because the contribution of those who are still poor is through their own efforts and that is regardless of which technique they will use at this time, and the example you gave is an example that makes a lot of sense and still happens this year where countries those who are able to process raw materials into ready-to-use goods will always buy raw materials in poor countries to be sold at a higher price after being processed through the technology they have.