From what I remember (that was almost almost 10 years ago, so a bit foggy now), it was some finance/trading people (the crazier stuff is always from finance people) that were doing some optimization work and found they had better performance by putting back the values in the macro itself and rerunning it. Something to that effect. (Or was it for versioning? I forgot the details honestly)

I think they were using file system calls with some tools to rewrite the file directly. But IIRC it's possible to do it just via the API.