People tend to have this doe-eyed vision of multiculturalism. When they think of multiculturalism they think about exchanging cuisines, languages, music, dancing, fashion etc. Who could be opposed to that? Thing is, there is a lot more to culture than that. It's also how you view the rule of law, about corruption and playing fair, about the value of human life, about the role and status of women in your society, etc. That doesn't just vanish because you happen to move to a very liberal country.

What they've effectively done is invited millions of people who would be considered more extreme than the far right by European standards into a very liberal society.

Going under the assumption that you can just mix your very liberal culture and another very conservative culture, and still end up keeping your very liberal culture when the immigrants have no desire to properly integrate, is absolute folly.