The article terms them self-assembling nanomachines. It might be more helpful to think of them as tools with a specific purpose.
So if you have, for example, cystic fibrosis, you have a defect in a cell channel called the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) and its job is to handle traffic of specific molecules into and out of the cell.
So your question is a little like asking "Why can't the cell just spit out random tools that randomly do different things?" And the answer is that it's not helpful to the cell if wrenches sometimes randomly morph into hammers or screw drivers when you ordered X number of wrenches because DNA is the blueprint instructions for creating this tiny little factory of life called a cell.
It's coded to create wrenches and it's coded to create a specific number of wrenches and it's not necessarily more useful for misfolds to turn into random other tools instead of the pile of junk that misfolds create.
So if you have, for example, cystic fibrosis, you have a defect in a cell channel called the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) and its job is to handle traffic of specific molecules into and out of the cell.
So your question is a little like asking "Why can't the cell just spit out random tools that randomly do different things?" And the answer is that it's not helpful to the cell if wrenches sometimes randomly morph into hammers or screw drivers when you ordered X number of wrenches because DNA is the blueprint instructions for creating this tiny little factory of life called a cell.
It's coded to create wrenches and it's coded to create a specific number of wrenches and it's not necessarily more useful for misfolds to turn into random other tools instead of the pile of junk that misfolds create.