Good thing they don't evaluate housing costs or the list would be completely different, as all of those top 10 cities are prohibitively expensive. Calgary might have been the only one of those cities in the list lol. ,...Melbourne maybe.
The main consumers of the list (the ones who actually pay for the full data set) are HR departments of large corporations that are relocating people internationally and need some independent benchmark of how nice or crappy a particular posting will be.
So, the list is pretty much meant to answer the question of how nice it is to live in a city if you are the kind of person that gets a paid international relocation from your company, ie upper middle management and executives.
It’s not quite the “how fun is is to live in X city if money is no object” … so you don’t see London, Monaco, New York, Hong Kong at the top, even though billionaires seem to enjoy having houses in all those places.
However, it’s also not a ranking of how nice it is to live each city is on the median income - a lot of the top 10 would drop off if that were the case.