Hah, I wish. Those were part of an old Art:Devlog , so all credit to @Minyi.
But would it be fair if a currently small guild posses a big chunk of land just because they were big and some point? You need to consider that all players, and therefore all guilds, share a finite amount of space, so you should be careful with mechanics that lock area away from others.
Therefore I think that the idea of material/coin based upkeep is quite neat as it gives small-active and big-casual guilds the same chances and doubles as material/coin sink to prevent inflation.