can't explain, but I can point to the discussion section of that paper, where that sentence is expanded and some of the mentioned cortexes (cortices? I don't know) are associated with presumed body/mental functions.

Variously I've heard those who work on brains (physically and mentally) say that locating function in a particular area is akin to Phrenology and has no place in modern scientific understanding of the brain. As an outsider that seemed wrong as brain functions are always described in pop science as being located strongly, but presumably the individual brain's adaptations make this something that can't be generalised too broadly?

The left brain / right brain thing is wrong, but different functions of the brain are definitely localized. This is seen in studies of people with unusual brain damage, and sometimes when sticking an electrode in a certain part of the brain has an effect.