Why Chinese pirate confederations became naval powers

Why were Chinese pirates powerful enough for Koxinga to seize Taiwan during the Ming-Qing transition?

They filled naval and local-control functions in regions where central authority was weak, distant, and constrained by governors' political incentives.

Pirate organizations could fill naval and local-control functions where government forces were weak. Governors had incentives to conceal deteriorating conditions because admitting failure could threaten their position or political faction. Distance made the problem worse in southern China, with powerful groups around the Pearl River operating weeks away from the capital. A governor who developed enough local military strength to impose order could also become a threat to the central government. The explanation therefore connects pirate strength with both weak control and the political penalties attached to admitting or remedying that weakness.