Actually - not true. Read the proviso
A pilot shall not ......
unless his licence includes an instrument rating (aeroplane) or an instrument meteorological rating (aeroplanes), fly as pilot in command of such an aeroplane:
(ii) on a special VFR flight in a control zone in a flight visibility of less than 10 km except on a route or in an aerodrome traffic zone notified for the purpose of this sub-paragraph.
Why do you think Class 'D' airports have entry / exit lanes notified? So bare PPL's, when the vis is between 3 & 5km (day) or 3km & 10km (night), can arrive or depart at an airport in a Class 'D' zone
provided they route via the lane and fulfill any criteria required for its use.
Also means they can fly circuits SVFR in the above met conditions.