Fundamental problem with DC-10 was the poor management. They made a stupid decision to make the cargo door open outward. Designed a complex locking arrangment using pins to be done by the cargo handlers. If not properly locked, the door flies off. The passenger door floor buckled when that happened. Very first time it happened the engineering team gave a very clean way to fix the issue. Pressure relief holes between passenger and cargo compartment, better locking pins.
But the management persuaded FAA not to issue a "must fix it" notice to avoid bad publicity. Gentleman's agreement between McDonnel-Douglas chief and chief of FAA. Never followed through. Happened again, law suits followed, all the dirty laundry got aired and they never recovered from that.
Added to that the airlines were using some home grown procedure to dismount and remount engines. Recommended process called for removing some 198 bolts. Airliners detached three loading pins on the pylon. In the process damaged the pylon. They had the engine on a fork lift truck while someone shouted directions trying to slide in the loading pin. The mistake was by the airlines. DC-10 paid the price for it. It got a reputation for being a badly designed unsafe aircraft. Only third world airlines like Biman Bangladesh would even touch them.
Good plane, killed by the same stupid management that killed US Auto industry too. At least in the case of US auto they were actively aided and abetted by the unions. But McDonnel-Douglas was just self inflicted wounds. The third player Lockheed (L-1011 tristar) survived on military cargo plane contracts.