Because what you are supporting is not your neighbors venture but the those who conned your neighbor venture.
I'm really surprised there isn't strongly worded statements from Mormon Leadership on this but instead there is a big Nu Skin sign on BYU cougar stadium (or was when I was last in Utah). That isn't good.
That being said every single printed congregational directory I've seen has a statement "For Church Use Only - Do not copy without permission from your local church leaders. Not to be Used for Any Commercial, Business, or Political Purpose" - So there is a strongly worded statement about using church resources for your business.
Or perhaps you were looking for this - https://www.mormonnewsroom.org/additional-resource/personal-...
Because it's a consuming and addictive negative expectations game that (generally) takes a persons money and effort without growing the social pie so to speak.
It feeds on persons natural desire to better themselves, to make it in life but this effort is subverted into the pockets of hucksters and scammers rather than actually producing good for the world. In this sense it's like pornography as it subverts a natural tendency into nonproductive or counterproductive outlets.
People become wrapped up in these schemes, they ruin relationships, families and lives. I find this very immoral.