Why arbiter has system-log file path mentioned though they are only used for vote?
The systemLog.path parameter is the path of the log file to which mongod or mongos should send all diagnostic logging information.
Since an arbiter is also a mongod instance that is part of a replica set, although it does not hold data, we specify the log path in order to capture the logging information for this particular mongod process.
Hope this helps!
Curriculum Support Engineer