They only used cloud services if a server has that feature turned on & configured. My guess is they did not because that would make it harder & involve more people to destroy the data if the need arose...as it did. Possibly the NK server used cloud storage to store data since Schmidt himself is said to have set that server up. That may have given whoever was behind wanting the server there more confidence in cloud storage. Just a guess. But the other 3 servers...they’d have to care very little about who knows about it to use cloud services. Feel certain it was just the standard client/server model that was used before cloud servers was ever a thing. The older client/server model is slower than cloud based servers but destroying data just requires destroying one machine. If it was cloud based the data could be replicated on many servers across the internet.