Ultimately, the visa officers have the discretion of making that decision. They do consider the medical officer's opinion seriously and look at that. They will often discuss it with us before making a decision if they are going to go against our recommendation.
Evidence of meeting #78 for Citizenship and Immigration in the 42nd Parliament, 1st Session. (The original version is on Parliament’s site, as are the minutes.) The winning word was services.
A video is available from Parliament.