Without these kinds of policies you'll just see the rise of more "new-right" parties like One Nation in Australia and Reform in the United Kingdom (yes, I am aware both are not "new", but they are newly popular). It turns out there is a sufficient amount of immigration that is disliked by the populace that they will dump support for long-standing parties in favour of those who promise change.
The UK far right got what they wanted with Brexit, yet they are still complaining. There's no evidence indicating that capitulating to their extreme policies will somehow lead to them becoming friendlier to the political establishment.
Honestly to me it seems that the objectively unprecedented migration levels in the UK of the last decade (caused explicitly by government policy) are better suited to be called "extreme" or "far" than the demands to roll them back