“ What i dont understand is why such countries advertise themselves as “welcoming” when in fact are pretty unwelcoming and closed.”

Good observation. Probably the answer is that it felt morally good in the short term. Many members of the “educated class” in Sweden wanted to feel good about doing what they believed was right, but just as long as it didn’t mean actually having to be too close to the newcomers. So they kept filling up the (in relative terms) unattractive remote districts and tried for a long time to look away while problems there built up and gang shootings and bombings became frequent

I’ve heard hypotheses about Sweden’s collective guilt about having helped the Nazis during the 2nd world war being a possible cause for the posture as “moral superpower” which shaped the politics of the later decades.