They allow 'twist' of the attachment relative to the tractor. In thier rigid or fixed position, the attachment like a rotary cutter cannot roll or twist, which takes a lot of stress and strain off the attachment.
If one side of the rotary cutter goes over a small hill or ground mound, it will try to lift that side of the tractor if the links are not floating a bit. Easier on the equipment if floating, and more flexible to hookup attachments if still doing that without the iMatch. /forums/images/graemlins/wink.gif