"TL;DR, this is using password guessing. Solution: use better passwords or urn off passwords altogether and use ssh authorized_keys."
Indeed and this is probably obvious and easy for high level users, but not everyone is and also there might be folks who've setup rsync and/or use scp with simple passwords for ease of management or might have take over admin of legacy systems that haven't been documented well and they might not be aware of all connections and their configurations.
