Ehhh it's a stretch to say all of MS-DOS's shortcomings could be over come by add ons. Many were intrinsic to the OS and fixes could only be simulated so long as programs and users agreed to abide by the band aids. It's also why so many things even in Windows 11 today are inelegant kludges to maintain backwards compatibility.
Fair enough. There was definitely a step function to even "real" 16-bit OSs of the minicomputer world (and ultimately *nix) that was just hard to make because of path dependency.
