The first time I used one was in high school when I was playing some video game in an emulator and wanted to convert the game save to another emulator's format, cause halfway through I realized the first emu had issues with the game. There was no conversion software, but with the hex editor I figured out that you needed to remove some header and change the endianness.
I grant that the post largely has a point, mind you. But scanning for a needle in a haystack is something that you just don't often do?
I am, of course, now very curious how often folks are using hex editors. And itching for an excuse to open a file that way. :D