[iflamberg]

с пендосской википедии

It is also considered an anti-pattern by some people, who feel that it is overused, introducing unnecessary limitations in situations where a sole instance of a class is not actually required, and introduces global state into an application.

It should be noted that this pattern makes unit testing far more difficult[9], as it introduces Global state into an application.

Advocates of Dependency Injection would regard this as an anti pattern, mainly due to its use of private and static methods.

In a nod to the concept of 'Code Smells', this pattern has also been known as the Stinkleton pattern.