I've been wondering, would it be possible, under the "Account Operations" section, to query data older than those last 8 days at the left-hand side navigation?

Yes, it would be possible but not with the normal Steem API. My goal is to have kind of a date-picker there in future, so that we also can choose a date range for the operations. Storing and indexing the whole account history comes with some crazy hardware requirements and I will definitely need much more space on my servers. With my current earnings and the low STEEM price it's impossible for me to order new hardware, but it is planned for the future.