Really walking back on that culture is fucking evil and has never done anything good stance eh? So we have established that your protip was garbage because culture has plenty of positive aspects, you just want to switch between definitions when it suits you.
“I was saying that, until humans won’t see their cultural differences as simple joke material, there won’t be a simple way to have a pacific coexistence between different groups of people living in the same region” If that is honestly what you were saying you failed utterly to convey that. Instead you said a bunch of weird things about how foreigners can’t change and refuse to integrate.
“Not everything is up to the state” thats not the point. The point is that states have in the past done exactly what you are praising. Taking children away from their families to strip all elements of culture away from them so they could integrate into “civilized” society. Deny them their language, their history. Anything that makes them different, beat it out of them. Literally.
You sound exactly like xenophobe bigots. Those foreigners don’t fit in. They are different and that is bad, they should be more like us. Conform! Though they will never really belong here.