That's not how it works. Loot and tracked events are completely separate until they are grouped by the output formatter, which can chose to group things however it wants, based on any of the data available.
Herein lies the problem hunter was talking about. Items are NOT grouped with the attendances they are part of. So for example: you are in an instance and do a start check every day, two days in a row, if trash mobs drop items both days (before any boss) then when you output the attendance from day 2, it includes trash drops from day 1 (because the attendance they were part of has the same name both days).
Personally its not an issue for me because I clear it daily, however I can see his point.