「Having an official seal shows the support of a well-known person. With this, even if someone can make fakes, their numbers will decrease sharply. At any rate, forging an official seal means committing a crime.」
In comparison to having a criminal record, making forgeries isn't just worth it.
Furthermore, there's the danger of being discovered in one shot when prompted to confirm.
There are no merchants who wanted to get involved in that, I think.
「I-I see certainly if it's like that....」
「There are other benefits too. Publish the fact that a well-known person uses it. Then, everyone will want to buy Malton-san's Reversi. If a famous person uses it, people will have more faith in it. Above all, it's human nature that they will want to own the same thing.」