Unlike bitcoin, from which Namecoin was copied, there are some very significant differences. The first is the need to register your own domain name in the .bit zone. Despite the low price (about 1 US cent), you will have to spend time to understand the system and choose a unique name.
The second point is a small number of DNS servers that support the required domain zone.
All over the world there are only 8 of them, which leads to their constant overload and inaccessibility for a number of users.