Hi Makigirl,
Good to have you around! 
You are right about the fake planes, I use them often. The problem is that these need to be hand placed, which might not be possible for big outdoor environments, especially forests. The same goes for the volume particles, also those would still leave visible fog around the light shafts. 
So that’s why I would be super happy if light shafts could be achieved with this automatic system, but without the fog.