There are tradeoffs. The advantage of learning smaller libraries is that you only have to learn what you need. However, the advantage of a monolithic framework

There are tradeoffs. The advantage of learning smaller libraries is that you only have to learn what you need. However, the advantage of a monolithic framework is that everything is integrated so nicely that, once you learn the framework, everything kind of "just works", and you don't have to spend time figuring out how to glue everything together. I personally prefer the former approach, but I also understand the appeal of a framework like Angular or Ember that makes all the high-level decisions for you.