I disagree. exFAT looks like a superb format for digicam cards, compared to the typical alternatives like FAT32 with their severe limitations.
Looking at Wikipedia, exFAT supports extremely large file and volume sizes, so I'm pretty sure it's suitable for large hard drives. I don't think it's suitable to run an operating system on it though. exFAT's limitations seem to me like they are more about the use than the size.