I find it very ironic your username is 'StopDisinfo.'
First, the idea there is no American integration is just funny, given millions of your countrymen moved to the US just 2-3 generations ago and yet French identity is essentially non-existent in the US.
In fact, there's more ethnically french people in America than in Canada, and yet Canada has very strong french cultural identity by comparison.
Second, I wasn't arguing against immigration and am not "far-right" (I'm absolutely pro-immigration), just explaining why Europe will never be able to do it en masse like the USA used to (they can't do it as much anymore either).
The reality: Socialist policy makes immigration an impossibility. The more socialist a country, the more aggressive its stance against immigration becomes. This is not a coincidence but a direct causal relationship.
People don't want to pay for random 2nd/3rd-world immigrants to suddenly get free healthcare, education and pension. It's that simple.
It's no secret that after America built its welfare state in the 1930s, this led to a dramatic shift to a closed immigration policy. And as the welfare state in the US has grown (from 25% of GDP in the 1950s to 35% today), the anti-immigrant sentiment just keeps rising.
European countries are no different, having grown their socialist welfare states dramatically over the past 60 years (from 25-ish% to 50% of GDP today). And thus, you get increasingly aggressive anti-immigrant backlash when times get tough.
The irony of the modern leftist is they don't understand the impossibility of their supposed beliefs. You cannot be both pro-immigration and pro-socialism. They are oil and water.
Either you believe immigration is a good force in the world, and thus want libertarian capitalist policy like the US pre-1930s. Or you want socialism, which leads to closed borders, and only pretend to like immigration to make people think you're a good person at parties.