> It means immigration at a rate high enough that it's beyond the capacity of the host nation to integrate the newcomers to its culture.

This resistance falls away quickly when food price inflation spirals out of control because you cannot find cheap labour for your harvests. (In 2025, there are zero highly developed nations, (yes, including Japan!) that do not heavily depend upon seasonal migrant labour to help with harvests.) Same when sick and elderly people have unreasonably long wait times at clinic or hospital due to doctor/nurse shortage.