Same thing that would stop you from pulling your pants down and sitting on a friend’s carpet or unplugging their TV and walking off with it
You do not understand what words like anarchy, communism or capitalism mean
Capitalism is not a natural occurrence, it requires a state to function, planning, control and above all violence; no capitalist would honor a contract if there weren’t courts to enforce them, no capitalist would feel secure if there weren’t state agents protecting their property, no capitalist in history would’ve been able to create foreign markets without European armies conquering the world
You fundamentally do not understand the depth and scope of these discussions, you read a definition in Webster and you think you know about the way the world works? But you can’t even see the obvious facts right in front of your face