Its not just the more money for the AI its also the quantity.
I am currently with Chosokabe and I am owner of 16 regions but l only can maintain/recruit units for 3 full stacks due to the unit recruitment limit. When I reached now Kyoto after really long campaign gameplay I see that Ashikaga got 2 regions only but got 7 stacks !!
It doesnt matter if half is just cheap Ashigaru it is the huge number of armies that shocked me.

The other enemy factions also got 5-7 stacks each all near by Kyoto. What can I do with 2 stack vs 20 stacks ? (my 3rd stack is a backup for my home territory)
Its a pity I got a lot of regions and huge cities and a lot of money but cant recruit currently any more units (except very few more HA+ bomb thrower).
