No, I don't think so. Accountable Government has had various titles over the years, but it's a document that was first produced in 1974 by Prime Minister Trudeau. It gets updated every time there is a change in prime ministers, and occasionally in between, when certain things change in the landscape.
For example, the 2008 guide contains annexes on ethical conduct and political activities that were introduced in the 2007 version of the guide. This was introduced as a result of the Federal Accountability Act, which was based partly on the Conflict of Interest and Post-Employment Code for Public Office Holders. It took part of that code and legislated it. It left the ethical guidelines part unlegislated. At the time of the Federal Accountability Act, the government had announced in its action plan that those ethical guidelines would find their way into accountable government, which is in fact what happened once the Conflict of Interest Act came into force.
So no, I don't think you can trace the existence of Accountable Government to any view that there's an insufficiency in the Conflict of Interest Act. It was all part of a regime designed to legislate certain things and leave others to judgment.