Yuuki4
Ah, i see what you mean. (nice clear example btw)
I did a bit of research (fancy googling sir). Yes, the Render Emitter switch is the one I was thinking of. And it turns out that while turning it off prevents rendering the direct view of the emitter, it does not remove the geometry, so it can still interfere with other raycasts (and is visible in reflections !?).
I understand the example you showed us is exaggerated, but that is damn big spotlight. Obviously you could go with a smaller, or further away with a tighter beam angle, with higher intensity and that could emulate the lighting effect you showed, and the shadow from environment or other lights would be less noticeable/out of frame.
Apart from that, the only suggested "solution" I found was the one you are already using: emissive surfaces with low cutout opacity.
I guess that if spot or point lights are what you need to use in some situations then the only thing for it is to treat the set as a "real world movie shoot", and move lights around for different shots. Note that you can setup lots of lights in the scene file and hide them completely for some shots by using the "eye" icon in the scene objects list, then they don't affect anything.