I found this little pearl of a line hidden in the belly of static_modifiers.txt:
So it seems CoT-hoarding is out in EU3, if you want to be able to use your merchants at all...
non_culture_cot = {
merchant_compete_chance = 0.15 #Each non-culture CoT controlled reduces compete chance by 15%
}
So it seems CoT-hoarding is out in EU3, if you want to be able to use your merchants at all...