jQuery is the king of "quick and dirty" (TM) - both by bringing ease of development to a huge community of young developers (when HTML was the thing that an up and coming geek needed to know and "dynamic HTML" was how they learned software development) and with poor plugin syntax that relegated modular design to a bunch of string handlers and magic functions, and lumping everything under a huge messy namespace.
Today, we know better. Developers have grown up and try to use good modular design with Javascript module loading, strict name spacing and micro libraries that embrace the UNIX way - do one thing and do it well. In such an ecosystem, jQuery is seen as a huge kludge.