From what I could gather from the article (i read Norwegian) they closed down the Presto department by offering everybody either a move to a different department (mainly mobile and desktop clients) or a severance package. At this point 50-70 people chose to leave. Since then they've also interdependently gotten rid of various other, both technical and non-technical people, for a grand total of 90.
I just don't understand what kind of crazy thinking would go into this.
They did not offer everybody to move to a different department. They did offer a that to a lot of us, but not to everyone. Most of those of us left were offered severance packages (which were said to be voluntary, but AFAICT most of the people who got offered one in the first round took it).