It's not a nostalgia-based emotional argument. It's real:

Half of the middle-schoolers in Vienna (Austria's capital) are now muslim:

https://www.heute.at/s/494-der-kinder-an-wiens-mittelschulen...

In France the DZ (Algerian) mafia is powerful enough to violently intimidate prison personnel and attack prisons:

https://www.latribune.fr/la-tribune-dimanche/societe/attaque...

In Netherlands, "Mokro" (Moroccan) mafia forced the heir to leave the country, after putting a price on her head.

https://www.wsj.com/world/europe/europe-drugs-gangs-organize...

So yeah, I guess that some locals can not commune together with you about the immense benefits unrestrained immigration brings to their countries.