"Crackpot" theory is a little harsh. It was a thing for a while when history did one of its "everything is wrong, let's start from scratch" things a few years ago. It was always at the extreme, iconoclastic end of history/archaeology (and some archaeological theories have always been a little "out there") but it was a school of thought for a while. Never a good theory, but definitely a theory and it helped to reset the debate a little bit.