Back in the MFIF days when this policy was initiated (for exactly the reasons given by alternaut) it yielded the additional benefit that tons/tonnes of articles originating from other sources would no longer have to be stored on MFIF's (and now FTM's) server. Moreover, nothing disappears from the InterWeb. Even if TVNZ doesn't leave such pages up, usually Googling it will bring up a cached version (ie, Google saves everything — I was even able to dredge up a disgruntled employee's diatribe against a former employer which had been removed by management on kijiji months earlier because it was defamatory).
