"Cant the erratic behavior of the transistors (eg flawed ones overheating)" Yes but that is either a manafacturing defect (if persistant) or a transient error,

"Cant the erratic behavior of the transistors (eg flawed ones overheating)" Yes but that is either a manafacturing defect (if persistant) or a transient error, or running out of speced tolerances. Or simply details of reality. Whereas a logical design flaw, is more the actual design/implemenation, is fundementally wrong more akin to a bug.