yeah that's true but it's a stupid concept and nobody should be forced to have a 'casus beli' to have fun and do what they want with their country. declare war on someone? react to it yourself or have the NPC countries react to it (should the RP host do that, that is)
the idea of a CB is that it puts down a guideline for your war goal along with a political shield for you to use in defense of your war
in this case the CB is, as previously mentioned, imperialism
it doesn't have to be a genuine moral plea, or a good excuse really
from wikipedia: In formally articulating a casus belli, a government typically lays out its reasons for going to war, its intended means of prosecuting the war, and the steps that others might take to dissuade it from going to war. It attempts to demonstrate that it is going to war only as a last resort (ultima ratio) and that it has "just cause" for doing so.
i'd say that sounds a lot like italy when the balkans nations ignored its demands
I would've been fine with declaring on the netherlands for no stated reason by the way, but I'd rather there be a reason behind it for rp purposes, it just looks strange if I don't but I don't see it as needed
essentially this
again, CBs are all political. there shouldn't be a hard block if you don't have a CB manufactured, and even then, anything relevant can be a decent CB
they /do/ mitigate foreign disdain if it's a good CB though