I don't believe anyone should "rely" on supplements, but I do believe that intentionally avoiding high-quality supplements designed to support certain goals is giving yourself an unnecessary handicap towards reaching your goals.
No, because most supplements have a legit tangible (if not nearly-immediate) result. There's a noticeable difference in my performance and recovery when I use Plazma or Surge vs when I don't. I feel a difference after I drink a Spike vs when I don't. I can even feel when I bump up my Flameout intake compared to when I don't (joints feel significantly better).
Those boosts, even if they're 2 or 5 or 9% better than I'd otherwise be, add up over the long-term. People have certainly gotten great results without any supplements, but trying to do that in today's age is kinda like saying "Hey, Lewis and Clark made it to California just by foot and boat, so I'll skip the airport."
The intelligent and strategic use of high-quality supplements will amplify hard work, but they won't de-prioritize it. Put The best supps on top of a crap diet and/or training plan and you still end up with crap results.
Placebo in the sense that they don't actually work, and your body only "thinks" they work? No. Creatine, for example, is probably the most thoroughly-researched supplement in the last 20 years and it's repeatedly been shown to be effective and useful.
Something as simple as caffeine has also been repeatedly shown to provide measurable results in performance. A small number of people might be "non-responders" to a certain substance, but that doesn't mean the substance should be considered ineffective for most.
You really need to brush up on your history, especially if you're going to be selling supps. Frank Zane was a huge proponent of vitamins, minerals, and individual aminos. The running joke at the time was that his nickname "The Chemist" allegedly came from his education in math and chemistry and his diverse use of vitamins/amino supps.
Vince Gironda and Rheo Blair (Note: Blair worked with Sergio Oliva in the late-1960s) were also advocates of protein powders and vitamin/mineral/amino supplements and had bodybuilders using them as far back as the late-'50s.
One last bit of learning about the industry you're involved in: The O.G. bodybuilder Eugen Sandow wrote about the benefits of "Plasmon" in the early-1900s, and that was basically an egg white or whey-based protein powder. Arthur Saxon wrote about bovril, a beef extract relatively-high in aminos, around the same time. So, yeah, supplements have always been part of the lifting game.