This might be a little controversial, but I think a large part part of the blame here lies on complacent center left parties here.

I think this is pretty naive.

I think it's the opposite. I think the further left push and the alieniation of the people in the middle has pushed those people to choose a group that will take them.

This for example happened wildly by the "bernie or bust" crowd in the US. They alienated everyone in the middle by saying our way or the highway.

The other facet is also that populism/identity politics in general is attractive to peoples emotions. Feeling part of a group that will accept you blinds you from reason. You've seen this in history for thousands of years between tribes, religions, nations, etc. I would also argue that populism brings on more populism in a pendulum style and that's why we should embrace globalism and individualism as alternatives.