All languages are decentralized regardless of regulation by official government bodies.
The role of regulation is mostly a legal role employed by countries that use a civil legal system. Most English speaking countries use a common law legal system and so interpretation of words is fairly fluid and subject to interpretation by the courts. Civil law does not have this kind of flexibility and room for interpretation, so courts will make use of regulatory bodies to uniformly interpret language.
This is why almost all countries with a civil law system have a regulatory body, while countries with a common law system do not.
The role of regulation is mostly a legal role employed by countries that use a civil legal system. Most English speaking countries use a common law legal system and so interpretation of words is fairly fluid and subject to interpretation by the courts. Civil law does not have this kind of flexibility and room for interpretation, so courts will make use of regulatory bodies to uniformly interpret language.
This is why almost all countries with a civil law system have a regulatory body, while countries with a common law system do not.