What is the scoop on megapurple and powdered tannins?

I am a wine buyer and on a recent in depth tour/barrel tasting, a winemaker showed me a collection of products they use that concerned me a bit. The "collection" was a countertop in the lab full of powdered tannins meant to enhance the wines in various ways. I have been a huge fan of these folks wine for some time now but I feel uncomfortable about the idea of using a synthetic (?) additive to flavor the wine. It seems like most winemakers are hush hush on this subject if they use the powders at all. Are these powders controversial? It seems to me that if you aren't able to get the flavors from the barrel aging processes, then you shouldn't just add powdered american oak barrel tannins to your wine to make it taste as if you're a master. Although the wine was delicious, I left feeling lied to and cheated. ALSO, what is the deal with megapurple? Are winemakers using this g outside of large output commercial type wines? How can you find out if a winemaker is using either one of these products?