jQuery is a great library. It came to be around the time when IE6 was the number one browser. Back then, there were quirks and differences that were tedious to work around and jQuery was the perfect tool for writing cross browser code. Today, however, web browsers have advanced a great deal from those days. We can comfortably use all features provided by ES5, and we have at our disposal awesome HTML5 APIs that make working with the DOM so much nicer. Developers are now at a position where they can choose to leave out jQuery for some projects, and still retain their productivity.