Sewers, designers and distributors may benefit from increased output. Consumers may benefit from a fall in the price of clothes. However, this does not provide a rationale for government involvement any more than a productivity improvement in milk production. Others will capture the benefits of one producer's actions, without paying for it. They will free ride on the knowledge generated by the investor.
Competitors can mimic the innovation, without undertaking any outlay.
Any profits made by the investor will only be maintained in the short-run. Profits may be eroded so quickly that the investor does not recoup the cost of innovation. Knowing this, the investment will not be undertaken. Producers further down the process chain may benefit, by receiving cheaper inputs. However, the innovator benefits as well .