I see this in a lot of small businesses and i just really don’t get it

It’s always phrased like “don’t ask what Brand/where we get our stuff is go do your own research” like… is getting advice from other artists not considered research?

I just genuinely don’t get it, how does it harm someone’s business to share what brand of gems or clay they use, or what website they buy from? And if they don’t use just a few then they could just say they don’t use a specific brand? Isn’t the whole point of making stuff the quality of what you do with the supplies and not just the materials? I mean you can give two people all the ingredients for bread but if someone doesn’t know how to make bread they won’t be much competition for the one who does,

I feel like maybe it comes from a point of “I want you to buy my stuff instead of make your own” because obviously not everyone who crafts is gonna sell what they make, i just really don’t understand the goal of withholding information like what brand of marker or paint someone uses, I mean if they spent so much time and effort trying out different materials wouldn’t it be more sensical to not make others go through the same issues and share your knowledge???

I don’t mean this from a hateful perspective i just find it a little frustrating and confusing