My comments are not so much about why FATE was corrupt.
I'm not trying to find any extra reasons for why FATE did what FATE did, but more pointing out this observation, that begs some thought. Even if it's not true or meant to be so, it does demand a second look. It's a pretty interesting find.
I'm using the tendency of a machine from this time period to become corrupted, as a supporting piece of evidence to show that (even if it's not canonical) Atropos might be at least part of FATE. The reasons I stated above would make common sense. Feel free to set me straight if I'm off base, but give me something to look at that reasonably refutes the suggestion.
Here are some other evidences that the creators of Chrono Trigger made Robo (Prometheus) at least in a way similar to his Greek mythological counterpart:
Prometheus in Greek Myth / Prometheus in Chrono Trigger
Was a Titan / Starts with a "Titan" vest
Defied the greater power (Zeus) / Defied the greater power (Mother Brain)
Played a central role in creating and assisting humans, giving them power such as fire and other civilizing arts / Rescued the future for humankind repeatedly, giving them the opportunity to live
Zeus punishes him for rebellion / Mother Brain punishes him for rebellion
As an advocate for humanity he gains semi-divine status at Athens / Fiona's shrine anyone? Immortalized in FATE?
Took fire away from Zeus (something that was believed to be unspeakably powerful from the gods) / Keeps Frozen Flame away from FATE (something that was believed to be unspeakably powerful)
Hopefully this at least shows some of the aforementioned similarities. Wouldn't it stand to reason that if the creators wanted to make Prometheus have some similarities to the Titan from Greek myth, that another character, so closely tied to him in C.T. might also have been given parallels to her counterpart. While they're both robots, Robo is implied to be a boy robot, and Atropos a girl, which both also match their myth counterparts.
Does this make sense? I think so, let me know what you think : )
***Modified for clarity***