This is indeed correct behavior. I have been encountering it in offline rendering in years. The key habit here is to realize that there are no 100% saturated colors in the real world. It’s kind of similar rule to albedo, where you should never use absolute blacks or 100% whites when it comes to PBR shading. If you are after heavily stylized look, then you can indeed revert to the old tone mapper, however from my experience, these PBR rules only rarely interfere even with stylized scenes… It generally just looks more natural to the human eye 
Simply, just try to avoid 100% saturated colors for anything, mainly in lights and materials.
BTW it’s not just “incorrect appearance of film”… It’s general response of vast majority of cameras… not just movie cameras and their films. Just search “red laser pointer” on google images, and you will see that every single photo of a red laser glow will have this exact effect. You won’t find a single photo that has just even flat red glow, unless it’s photoshopped in for product shot.