millions of tons of sulfur are purchased and delivered every day without anyone noticing . . .
Who's "nobody"? People selling and buying the stuff notice. People hauling it notice. Same with any raw material.
The industries buying and using that sulfur certainly notice and they'd certainly notice if a substantial quantity of their supply were diverted, thus causing the price to go up. You know when I found out that airliners were going to carbon fiber composite skin instead of aluminum? The price of carbon fiber kayaks, rowing shells, skulls, paddles, etc... shot up. Our little tiny low volume niche market of racing watercraft were certainly affects and noticed when a substantial supply of our raw material got diverted.