Complex sentence: The ryotwari system had the advantage of removing the zamindar middleman between the government and the farmer, who too often acted as a screen behind which oppression could go on undetected.
Split into simpler sentences: The ryotwari system had the advantage of removing the Zamindar's position as middleman between the government and the farmer. The Zamindar too often acted as a screen behind which oppression could go on undetected.