i think what soundillusion is saying is that OEM (and aftermarket) projectors using conventional bulbs do not need washers
modern OEM HID headlamps on the other hand, projector style or otherwise, need washers
sticking HID bulbs in normal headlamps designed for conventional bulbs can cause glare as the beam pattern sometimes isnt brilliant, and isnt road legal (although would pass MOT if beam pattern is ok)
but using a purpose designed HID/projector lamp unit and modifying a mk2 lamp to accommodate it? now thats a grey area!!