The article actually tells you why they're doing it. They've built up a database of the relative levels in wines over the years - and that allows them to test any vintage bottle and make an estimate as to whether the label has been faked - and the wine is actually something from a cheaper year.
Remember there's serious money involved in this. My Dad bought a case of 96 Chateau Lafite for about £2k as part of his pension investment in 99. He decided to take a couple of riskier punts with small amounts. Sold it for over £8k ten years later. There's quite a lot of incentive to commit fraud when single bottles of vintages are going for £1,000 or more.