The popularity has wained. For a couple reasons. They are a mid length case that usually requires them to be chambered in a long action gun. If buying a long action why not go for a case that has more capacity and thus better performance. A 25-06 over a 257 Roberts, or a 280 Remington over a 7x57 Mauser. Add to that the newer cartridges like the 260 Remington that duplicates the 6.5x55 or the 7mm-08 that duplicates the 7x57 but in a short action rifle. Factory loadings that are kept to lower presures due to older weaker guns also contributed, a handloader can soup them up but if you don't reload your stuck with weak loads. And of course MAGNUM MAINIA is a factor too.