Island,
I remember back in the early 1970s when the very 1st fine wire sparkplugs were introduced. Champion mafe them and they were gold tipped. Lots of people claimed if they wete so good the car and motorcycle makers would put them in their product at manufacture. Didn't happen. Yet when you'd install them in an engine . . they worked so well that you had to adjust the idle lower because they were so efficient.
Your rational that manufacturers of fuel would use adfitives if it was such an improvement and benefit is that same faulty logic. You lump all additive products and manufacturers into the same group . . and of course that logic produces a murky and clouded negative answer for your purposes.
You claim any and all additives are voodoo yet you have no empirical proof to make such a claim. On the other hand, there ate many 1st person witnessed accounts of seeing differences in use and performance when using certain additives. Your claim there is no proof is based purely on a lack of published testing by ?????
Meanwhile 1st person observation is not acceptable in your mind. That just isn't logical evaluation or reasoning imo.
Even the concept of declaring all additives from all manufacturers as "voodoo" . . in itself . . is claiming that anyone who uses additives is unaware. And again what is your research to support such conclusions ? And just how many products of how many manufacturers are you lumping into the "voodoo grouping" ?