What I want to know is why the computer run remotely supplied code. You can try and crash the computer I am on, but my two development machines (one controls m

What I want to know is why the computer run remotely supplied code. You can try and crash the computer I am on, but my two development machines (one controls my own custom hardware) have no network connection, you would have to break into my house to do harm. Why are these system not isolated that way?