This is the difference between the proposed light shader and the one I conjured up with the LightFalloff node.

I would like users, in their spare time, to play with both setups and determine on their own which arrangement may fit their needs.  There are too many permutations to demonstrate here, but I will give you my assessment of the difference between the two shaders.  Shvrdavid gives a convincing demonstration and it works fine, except there are finite limitations with the math.  It is stated that Value2 controls the distance of the ray length and it works well to an extent.  The higher the value, the more far-reaching the light ray.  However, notice that this math node is attached to the Factor connector of the MixClosure Node which in turn is connected to Emission and TransparentBsdf nodes.  The TransparentBsdf node controls the transparency of the object emitting light, may it be a ball, cube, cylinder, etc, thus hiding it in the scene.  The Factor range limit value is 0 to 1.  The Math node does a fine job controlling the value ranges for the Factor keeping the object invisible, however, when the Math node Value2 is increased to 7 and beyond, the TransparentBsdf node is triggered off and the object appears in the scene.  If primitives are off-camera, there are no rendering issues, but if there are intentions to light the furthest distance with the emitting primitive on-camera then it will appear.  In this particular case, it would be advisable to uncheck the Visible In Camera box of the object under Properties to avoid this annoyance.