Ok I think I found the answer
The company I was looking at is based in China.
Chinese company law:
Article 46 The term of office of a director shall be stipulated by the company's articles of association, but each term of office shall not exceed three years. A director may, if reelected upon expiration of his term of office, serve consecutive terms.
And this following from a Chinese law firms website explains the thinking behind it.
The supervisors did not exist in the very beginning. In modern companies where ownership and management/controlling rights are separated, the shareholders who enjoy the ownership benefits cannot always take part in the daily management of Companies, and would have to entrust the standing board of directors to manage and control the company. In this situation, the directors’ power will be too much. In common sense, “Power tends to corrupt; absolute power corrupts absolutely”. So to prevent the directors to abuse their powers and put their own benefits above the benefits of the Company, the Supervisors come into being, who are appointed to supervises and monitor the policy-makers of the directors (and the managers they hire).