I have to disagree with you on your "reading data is a change". The act of reading is simply read. By looking at the data, you do not change it. You may request a business logic change in the application or the report itself, but that is seperate from the report.

"It has always seemed a foreign concept to me that reporting systems were somehow "different" "

Reporting Systems, good ones, have a different focus on the data model than transactional systems. You design a report data model to be quick to read from, where a transactional system has to be designed to benefit inserts/updates more than reads IMHO. If your application is not a transactional system, there may be some synergy between the report model and your application data model.