Do you believe that when we all lived in huts that the feudal lord would send out knights to defend you if your neighbor decided to take your property?
Under a medieval feudal system, most people did not own property the way we think of it today; the feudal lord did. If the lord wanted to take all your clothes and throw you off their land, they could, with impunity.
That said, yes, the feudal lord's band of merry thugs would keep the peace, because peasants can work harder if they're not squabbling with each other.
It's not that clear cut. If a poor person gets robbed today the cops will do basically nothing. Feudal lords will defend vs Viking raids. So, they both sit betweeen 0 and 100% on this.
That said, yes, the feudal lord's band of merry thugs would keep the peace, because peasants can work harder if they're not squabbling with each other.