No, you're mistaken. It is actually a very big problem. Earlier on the same page you linked to, it explain that "ICANN approved the Internationalized domain name system, which maps Unicode strings used in application user interfaces"[1].
As a concrete example, the following are fake links to Wikipedia (and entirely equivalent):
It is true that network protocols encode these internationalized domain names in a subset of ASCII, but the user sees Unicode in his browser address bar or email. There is no restriction on how applications (like browsers) display domain names[2]; they can use Unicode if they want. This lead to all sorts of devious attacks[3].
