Cultural, religious and ethnic homogeny are all obviously very beneficial for social stability, and I think the homogeny of Scandinavia is one of the main reaso

Cultural, religious and ethnic homogeny are all obviously very beneficial for social stability, and I think the homogeny of Scandinavia is one of the main reasons that its social approach to managing crime has been so successful up until now. With the other major difference being that involuntary institutionalisation is rather high in those countries, where a lot of the anglo-sphere has instead opted to just release those people to live on the streets. These are however massively controversial ideas to a lot of people. Singapore also proves that you can establish an incredibly high level of social stability without that homogeny though (and even with massive inequality), as the composition of cultural, religious and ethnic diversity they have has been a source of instability and violent confrontation for nearly every other country in the region.