Is the common knowledge about fallowing farm land wrong?

Way back in the day I was taught in one sentence in a textbook that farmers from the beginning of time let their fields fallow every other year or something to allow the soil to be replenished. Not being at all involved with agriculture it begame a bit of trivia I could recite, but was never interesting enough or relevant enough to further study or question. But the book I’m reading now, in it’s discussion of the effect of agriculture on the propogation of disease, dropped a somewhat venomous dismissal on this justification of the practice saying the amount of time it would take for a fallow field to be replenished was laughably longer than they were typically fallowed. I think he said the real purpose of fallow had something to do with purging unwanted plantlife (and possibly parasites?) with the sort of brute force attack that couldn’t be executed on an active field. I think, according to him, there was some pretty hardcore manmade flooding involved at least some of the time.

I’d never heard that old explanation challenged before, but the premise seems plausible. However I’m not finding any material elsewhere to corroborate this challenge or even confirm that there was even a little controversy on the matter any time ever.