The dumbest mistake the western countries made when establishing nation states were their open immigrant and assylum system . Having known all human behavioral science they missed on this. They thought‘assimilation’ will follow immigration . Yes Africans started wearing T shirt and Coat and suite. Other than that nothing happened
Once in reasonable numbers Natural way the humans organize aroud the same ethnicity and start their cultural practices and way of living.
‘Assimilation’ is unnatural expectation for human beings . Other than Low IQ Africans started living imitating whites there were zero assimilation from any other ethnic group
Gulf countries were clever to understand this and they framed their immigration around that and there are strictly no citizenship or residency only expats .
That will prevent immigrants from intruding into host culture and safeguard attempts of cultural take over
Look at Gulf nations. No riot, peaceful co existence without being citizens
Western countries missed the opportunity