I need to assume Jake is right:
When increasing camber by adjustable top mounts you also change the 'strut angle'
'SAI' (unfortunately I only know the German word 'Spreizung') at the same time.
This is the angle you see on the right picture and it's in the 15° area on a Mk.V GTI.
The point is this angle also defines the position of the roll center as shown above.
For maximum cornering grip more camber is more important.
I wouldn't overestimate this, but it seems Jake has set an interesting point on this.