Incorrect? That depends on how you look at it: the raw registers what the lens told the camera. In the case of pre-digital lenses, that is “nothing”.
In addition, adding those data later means that the chance of errors is larger (do you remember which lens was used, which settings you used for the lens, and do you always spell the name the same?), and wrong info is worse than no info…
Oh, it’s possible, even quite easy, to alter raw files. But if even a well-known camera brand manages to provide a raw editor that damages its own raw files, I prefer to err on the side of caution…