I've used it for years. At one point, in Montreal, we had a large aquarium store that had terrible cheap sickly fish, but the best DIY gear and cheapest good quality equipment I've ever seen. If you wanted to invent, that was the place to go. They took a big risk and were bringing in Chinese manufactured filters and other equipment when people were convinced the US brands were better. Consumers didn't realize they were made in China too. I got brilliant equipment from them, including some no name HOBS still running 20 years later.
I found Japanese filter matting there and liked the look of it, and its recycled nature. Every non air driven filter I have has that stuff in it.
It is murder to cut, and could only appeal to DIY oriented people. Most aquarists waste money on filter inserts, pushed by an industry that painted itself into a corner. The quality of an aquaclear HOB reached the point where you bought one, and it ran for 15-20 years with no problem. That wasn't ensuring the sellers any ongoing revenue stream, so all the manufacturers had to 'devolve' their offerings and make them lower quality, slot insert machines that keep you buying replacement media.
Japanese filter media will outlast anyone who buys it. So it will never be marketed hard, and will never be in pet stores.