If you honestly think this is a significant driver to inflation, you fail economics forever.

FC housing is roughly 30% of houses owned. That's 1728 houses per server. Lets say a tenth of them are doing fight club. You can talk about "ward full of shell FCs" all day, but in reality, that's one ward out of 96, and most servers don't even have this happen, period. So with a tenth of FCs doing fight club, all day every day, that's 173 gil printers going brrr.

A single sub will get you about 100K a day. That's about the same as coffee biscuits. Each FC has four subs. So this problem is roughly the same as 692 players doing coffee biscuits. There are over 10K-15K people logging in on most NA and EU servers every single day. If a tenth of them are doing biscuits, then biscuits are over twice the inflation driver that fight club is.