If we take a look at SD cards, we've had the UHS-II standard for a few years now which can allow writing at 300+ Mbps. However only a dozen cameras currently support it, with most using UHS-I at most. Canon and Nikon also support CF, XQD, and CFast cards for their very top models, but most of their range lacks any options for truly fast data writing. As a result you're limited by your buffer size, which must be extremely annoying for anyone who's trying to shoot a large burst of pictures. Writing at 300 Mbps on the other hand can easily allow continuous shooting at 10 FPS in RAW for as long as you can possibly need.
So what's the reason for being so slow in adapting proper card standards? Is it so the manufacturers are able to force photographers to buy their top-shelf products? Or perhaps people like sports photographers just shoot in JPEGs and therefore don't care about the card speeds?