To be honest, not everyone wants to be a spell flinger or get one, and mages could work on their own agendas too, so in the end they aren't reliable either in an RPG sense.
Also Jax, Alchemy could be used for something like this, albeit not using the ingredients since everyone here has some idea on those pieces of lore.
Alchemy is a form of science that uses equations and regents.
If an Alchemist can alter someone in a way that they heal their wounds, akin to a Health potion, and harden their skin, aka. a Stone Skin potion, what makes it so hard to believe that nothing can affect the mind? A potion that affects your blood cells and harden your skin in such a fast manner that they activate instantly is more far fetched than a potion that can alter a brain's hormones or whatever goes on up there.
A potion that can literally control someone is more scientific and more closely related than a potion that can harden your skin to where when a knife cuts you all it leaves is a paper cut. This server is a fantasy server, a server where we have people who can fling spells from their fingers tips, drink potions that can let you see in the dark, and fight orcs who killed and ate your parents.
You should be able to make a potion that can literally mind control someone and it should be accepted, albeit, with proper lore and ingredients and how to make it. If someone can addicted to beer, coffee, shakes, or whatever, it deals with your brain because of dopamine. An Alchemist could literally make someone a zombie if they wanted to, so what makes it so that a truth serum is so far off? Yes, it requires both people to RP it, and yes, it may not always work, but the question is, why not? Why can't we have this? Simply because the OP does not understand the regents? Bah! Someone else who better understands the plant lore could make it, hell, probably even make new plants that would help in this area too.
Not everyone wants to go to or be a mage, sometimes people want to be a mad scientist, and alchemy could do that if you let it.
Let this idea into your hearts, and improve upon what this man has said.
An idea like this can be powergamed, but so can magic as well and any other function too, but there is a system for that, and it's called blacklists. If you think someone is powergaming, report it after talking with the person you think is powergaming. Conversation is key.