This shouldn’t be surprising. Horses are almost as smart as dogs, and dogs personalities are heavily dependent upon their upbringing.
Now you and I know rather differently, but those places are still going through their own 'journey of discovery' when it comes to animal intelligence and social benefit.
The above said, I'd have not expected a Finnish researcher to be one making such a 'new' discovery as Finnish culture does include extensive animal husbandry and dog/horse culture.