Patterns are not libraries or classes, they're concepts, reusable solutions to common programming problems, tested and optimized for specific use cases. As they're just concepts to solve specific problems, they have to be implemented in every language.
Every pattern has its advantages and disadvantages, and choosing a wrong pattern for a problem can cause you a big headache.
Patterns can speed up the development process because they provide well-tested and well-proven development paradigms. Reusing patterns helps prevent issues and improves code readability between developers that are familiar with the patterns.
Patterns have major importance in high-performance applications. Sometimes, in order to achieve some flexibility, ...