"Simultaneously to Steve Jobs’s introduction of the iPhone in January 2007, Google started publishing a series of blog posts called “Testing on the Toilet”. On May 15th, 2008, this series featured a famous issue: “TotT: Using Dependancy Injection to Avoid Singletons.” The writing was literally on the wall of toilets worldwide: Singletons are bad™®©. Sadly, the much more exciting idea of dependency injection contained in the article got lost in the minds of most readers."
https://deprogrammaticaipsum.com/the-hype-cycle-of-oop/