I dislike many of their policies but I'm not convinced this one is wrongheaded.
While meth (called 'P' in New Zealand) was often manufactured from pseudoephedrine tablets here, the outright ban on this medication did not seem to have succeeded in lowering the availability of P in the country; after an initial rise in price and reports of lowering of purity, the street price has overall dropped from around 700 NZD / gram in 2009 to around 400 NZD / gram today, as described here[1]
[1] https://newsroom.co.nz/2023/09/26/pseudoregulation-the-failu...