I guess you completely forgot where this started. Monarchists on the American continent happened in the late 18th century. As you point out the Magna Carta occurred in the 13th century. (The House of Commons was created in the early 14th century.) Monarchists in the Americas didn't think that monarchs owned all the land. Your argument is based on your delusions as you yourself has just shown us by admitting that the Magna Carta changed social structures. It's almost like you have a 12 year old's version of what history is.By the 19th Century most European Monarchies had retreated to parliamentary systems. This was driven mostly by the American and French revolutions. Even the nations not directly involved were swayed by these uprisings to loosening the grip of the Monarchy. Social structures were challenged as early as the 13th century with the Magna Carta. By the 19th century Western Monarchies were a shell of earlier times.
King George the I of England lost the absolute grip on property with the rise of the East India Company - that demanded sovereign control of their own property in the mid-17th century. The Empire depended on the EIC to fuel the empire and capitulated to the rising corporation. This was the beginning of actual private property in England, and later Britain.
It seems you think you are clever by telling me about peasant and landlord after I asked you about gutsherschaft. What you don't seem to understand is different monarchies had different systems. The Franks (Germans) had the monarch elected by the nobles in the 10th century. In most monarchies the kings rarely had the power you think they did. They were beholden to the landowners (nobility) for their power. But all of that is not relevant to the Monarchists that supported George III in 1773.I'm curious why you think you are clever? The role of peasant and landlord was critical to the feudal society. Land grants flowed from the Monarchy to various Nobles - as previously explained who had a host of underlings who then had landlords that directly oversaw the peasants below them.
The nobility could seize the lands at will should a particularly landlord displease them. The Crown likewise could and did seize lands from Nobles as the Crown saw fit - for any or no reason. The enlightenment and the age of reason of the 17th century saw the rise of property rights and individual rights as a cause - leading to the American ideals and the offspring of that in France.
Remember, Socialism is simply Feudalism rebranded to appeal to the stupid.