QA1 Six-Link Rear Suspension Conversion Installed

I am in the process of getting my dart in to this century. I looked at the QA1 front suspension and was quite surprised when they said their system don't use the rack n pinion steering, just the old steering box, center link, etc, etc. I believe QA1 is in fact a respectable name brand in suspension, but why would they try to talk me into keeping the outdated steering components. Is there a problem with putting a rack in? Some incite on this matter?