I don't know if it's necessary but it is a method that's been passed down the generations so I reckon there must be good in this practice. Even my Malay friends who have settled overseas still practise this when they are in confinement.
Param generally contains rice flour, ginger, tumeric and black pepper and some of those ingredients have anti-oxidating and detoxing properties. So there might be some truth and benefits to applying them :)