As far as Vizet knew, Magic Contracts were an extremely special type of magic, often capable of producing tremendously powerful effects—or extremely severe consequences.
Take the Fidelius Charm, for example. Its effect was astonishing. As long as the secret-keeper was unwilling to speak, no matter what magic the enemy used, they could not force the secret-keeper to reveal the secret.
The Unbreakable Vow was another good example. Once the terms of the contract could not be fulfilled, the person who broke the contract would die.
Books related to Magic Contracts were all kept by Hogwarts in the Restricted Section, and there was no discussion of their principles at all. They merely recorded how to establish Magic Contracts.
That Magic Contracts were placed in the Restricted Section was only natural.
After all, breaking a Magic Contract brought serious consequences. Students could very easily establish a Magic Contract on impulse, then break it on impulse too.
For example, two students fell in love and made an Unbreakable Vow to each other, and the content of the vow was still, "If you don't bring me breakfast in the morning, then go die"...
Those students' dormmate might one morning witness a scene unforgettable for the rest of his life: one of the pair suddenly dying because they wanted to sleep in...
The books on Magic Contracts in the Restricted Section would also have such a sentence appended at the beginning:
Please think clearly before establishing a Magic Contract, and ask yourself whether you are fully mentally prepared. Breaking a contract requires paying a tremendous price, without exception for anyone! —Albus Dumbledore
Even Dumbledore had used phrases like "tremendous price" and "without exception for anyone" as a warning. In fact, that also reflected from the side that Magic Contracts were an extremely troublesome type of