If some of the original criteria can be met by the person , like being able to remember at least some dreams at all ( which can be improve too) Lucid dreaming can be obtained without any outside chemical influence.
Most all that substances do is try to aid in the effort to Lucid dream. To add to that most of the effects are just hear say rather than fact. Some may indeed work and if an individual would persue it through those means then so be it.
It all comes down to what combination works for you! Unless ofcoarse it invovles harming your body.
Even if somthing is actually a placebo, who cares if it works for a particular person. Wether it be in the form of a technique an herb or a device.