Why is this not the solution?

[Almagnus1]

Probably the biggest cause of inflation in the game is the gil cap. There's no reason for gil cap to be 999,999,999 per character/retainer when the largest game controlled purchase price is only 50,000,000. That's an insane amount of gil that can be accumulated compared to the typical gil reward for game play (usually between 500 and 8k gil).

Part of this limit is a technical limitation, and as 2^31 = 2,147,483,648 (which is approximate 32 bit signed int limit), that almost 1Billion gil is likely a cap using a 32 bit int in a database with a number SE thought no one would ever hit. However....