theres a difference between projecting light intensity, and picking up projected light density to source.. If you projct intensity then the intensity of each light also changes within the projection space.
Yes it can be done its jut a little bit tricky as shading nodes per point calculations don't really exist dg time. Api can make them do that, but you can rather convolutely script this and build a huge network, or use a quite speed impacting expression like the particle grid solution.