currentOp currently return only the latest (current) operation being run and gives no evidence of the original command triggered by the user.

For example, if I am running aggregation command with $out. The currentOp could return the command as renameCollection, createCollection or aggreation, based on which operation is being run currently. It doesn't have any 'parent' field which can show the parent operation.

This means that, if a user wants to see if there are any agg operations. This is no accurate way to find out, since the results of currentOp are misleading.