[Humakty]

I do also think resource is important for many factions, as it allows you to make a bigger recruitment in a specific area of your empire/kingdom.

Not only will it reduce the micromanagement of putting your small armies together, you'll also save some months by recruiting directly in the fort who's the closer to the battlefront, being able to support a progresion in ennemy territory with rapidly set up armies, or to stop an invasion dead.

You also recover more rapidly of a crushing defeat, being able to transform your sudden increase in income into shiny new troops.

Even late game, it allows you to have a better equipped spell fodder, which can be usefull (apart against charm/domination spells).

After all, if your plans to crush your evil foes in a majestuous blitz fail (but it won't...), you can still expect to win an attrition war.(by recruiting more troops than he is)