National Records & Citizenship

I couldn't find much on a search but am really curious as to why
apparently National records are based on citizenship and not on the
location of the actual flight? This leads to very misleading listings
of National Records. For example the World Altitude Record of Fossett
and Enevoldsen of 50,721 ft was flown in Argentina but shows up as a
US Multiplace National Record when in fact no multiplace glider has
ever flown that high in the US. Similar with the 1500 km that Fossett
and Delore flew in Argentina. What was the FAI thinking when they
decided to use citizenship instead of the country where you start your
flight? Surely they had a reason.