The lighter platinum group metals are widely used as catalysts to produce large-volume chemicals. Off the top of my head there's methyl acrylate, vinyl acetate, acetic acid, many more.
Rhodium is especially scarce, palladium not so much, but it's a political metal, a substantial part of world production is not in the West.
Rhodium use would go up were it more available, lots of interesting chemistry there, and political security is also worth a lot, but extraction from nuclear reprocessing isn't happening. That's the intersection of politics and the markets, where markets become political.
Rhodium is especially scarce, palladium not so much, but it's a political metal, a substantial part of world production is not in the West.
Rhodium use would go up were it more available, lots of interesting chemistry there, and political security is also worth a lot, but extraction from nuclear reprocessing isn't happening. That's the intersection of politics and the markets, where markets become political.