I don't believe the Armenian genocide won a lot of converts. What they did was they abducted a bunch of orphans raising them as turkish muslims. I don't know how common a tactic this was. I do know similar tactics were used at Native American reservations, but I should note that while most Native-Americans are some form of Christian they retain their unique cultural identities.
It wasnt common at all. The genocide is focused on early 20th century, where nationalism is a hyper-drug. I wouldnt call it relevant to the game in any form or shape. Especially considering that this happened during a world war and in a collapsing multi-ethnical, multi-religious, multi-cultural society. Something you wont seen often, if at all, within the game.
I also don't think there should be a way to speed up cultural and religious assimilation for pure gameplay reasons. Because that'll just lead to everyone trying to convert these pops because it'll be mechanically simpler. It should only exist for historical religions. And historically cultures and religions have managed to be very durable. Judaism despite being a minority religion has survived these many millenia. The English tried to stamp out the Irish cultural identity, and yet it persists to this day.
This is why I despise the 'Cultural Unification' mechanic (though at least it's turned off by default now I believe) since I can't think of a single example of it being done in history. The Russians ATTEMPTING to do this is one of the reasons for the ongoing Russo-Ukraine War. Pretty much every attempt at forced cultural assimilation was more trouble than it's worth. About the only really 'successful' attempts was much more about settling people of your culture into a new region and producing more of your people than were there previously. Hence I think it makes sense to have players focus on this. An example would be in Ireland the formation of the Scots-Irish, where the English historically settled protestant Scottish lords in Ireland that would be more loyal to the crown- which is why Northern Ireland is protestant and remains a part of the UK. They didn't simply flip on a 'genocide toggle' to remove their problems with holding onto Ireland. And arguably every attempt to assimilate Ireland ended up furthering the cultural divide- despite both being english speaking christians.
I think one mechanic they could include though- I think religious tolerance edicts in the age of enlightenment could allow for cultural assimilation without conversion. An example would be how once constitutions guaranteeing religious liberty across europe came about (Courtesy of Napoleon) Jews for the first time could enter civic life as medieval segregation laws were shut down. Jews began identifying more as French or German than they did as 'Jews'- because being allowed to participate in the state gave them investment in it. So in this way, i could see under Revolutionary France the 'conversion' of Jews from Sephardic to French, while they maintain their Jewish religion.
It was most definetly an oddity to purge the locals, but it wasnt unheared of. Some examples:
-purge of jews/muslims from iberia.
-purge of muslims from Sicily.
-Mongol genocides.
-Timur rampage (also apocalyptic levels of mass-murdering & crimes, often forgotten)
-purge of the Hugenots.
You also have cultural unification/"standardization":
-Germans becoming more alike. No kingdom identification, but rather an identification as "one people". [in our history this meant the spread of prussian culture within Germany]
-Same above with the Italians.
-Standardization of the french language and identity (e.g. occitan is pretty much gone, so is Breton).
-Japan assimilation.
-Han-chinese assimilation of various conquerors. E.g. Qing, Yuan.
Spreading your culture is most certainly historically accurate in multie regions of the world. In particular the far-east and Europe. Specifically purging a group of people along religious lines is also historically accurate but far less common. I dont think we need the latter. The former can be discussed, but should come with a downside.
In EU4 you can accept a culture or convert it, which cost a shit ton of bird mana. So the downside is less tall gameplay.
As a side-note: A degree of assimilation was always the case. People wanting to climb up politically also assimilated (usually). Social mobility/Meritocricy can (as an example) be used for faster assimilation.
