[Robert986]

I see it as follows..

To reduce understeer on a oem car, first increase neg camber in the front. The car is setup with understeer "by design" via limited camber..

Technobrace and similar supports the rear "leg" of the rear subframes. The toelink is connected to this leg. The front leg on the rear subframe holds the LCA which is crucial for keeping the neg camber under heavy cornering. This front leg is already supported by a oem steel structure in front of the subframe.
So basically the technobrace keeps the toe stable under load.
A solid inner bushing for the LCA will further support camber under load.

One might not need a rear strut brace in most cases, however I've got cracks in the rear strut tower so after welding this, maybe a brace would protect from further cracks?