The parable of Chesterton's Fence and the parable of cargo cults are in opposition to each other.
One says "if you don't know what it does, don't delete it", the other says "if you don't know what it does, don't keep it".
One says "if you don't know what it does, don't delete it", the other says "if you don't know what it does, don't keep it".
The whole point of Chesterton's Fence is that there's wisdom encoded in the way things have been done. The previous guy who worked on the same module was probably somewhat competent, and in any case, the component was fulfilling business needs for all that time, so they were doing something right.