The myth is that 90% were involved in food production in any way. Butchers and millers and brewers and bakers are part of that 90%, they were not doing anything in any fields. But that myth is based on England under Roman rule, where vast quantities of food were grown by slaves and shipped to Rome. After the fall of Rome, people returned to farming for the local population, and so needed fewer farmers. The period is even characterized by the three orders: those who fight, those who work and those who pray. These were societies that had enough food production that a major portion of the population could spend their time praying instead of doing anything productive. And the "those who work" includes carpenters, blacksmiths, masons, etc. not just farmers.

And that's not what is in dispute anyways. Hoeing fields is. Farmer does not equal hoeing fields. Tillage was done as little as necessary, and was done mainly using horses or oxen pulling plows and cultivators. A hoe was used seldom, and mainly in the vegetable garden. As I said, we have actual period texts on how to farm. All the way back to Rome, Greece and ancient China. None of them describe the modern hollywood portrayal of mentally handicapped peasants spending their lives hitting the ground with sticks.

We also have records of actual farm manors and how much labor each farmer was required to provide for the lord every year. They worked less than us, and had 8 weeks a year without work which they spent playing sports and games in the village green. We have skeletons that show they were taller than us, which indicates better nutrition. But because the late 1700s and early 1800s saw massive numbers of people move to cities and suffer terrible malnutrition and poverty, everyone just assumes things were even worse before that. All available evidence says otherwise. Things have always been bad in cities, especially due to disease, but rural life appears to have been pretty decent and was the majority of the population. Localized famines were rare enough to be major historical events mentioned all across Europe.

If you are interested in the subject, I highly recommend https://www.amazon.ca/Life-Medieval-Village-Frances-Gies/dp/...