In the context of the tool analogy, you're right: we should pick libraries and not frameworks. However, many software projects are complex machines---and like

In the context of the tool analogy, you're right: we should pick libraries and not frameworks. However, many software projects are complex machines---and like real world machines they're made of parts. It'd better then to have a framework because the framework assures you that all these parts ought to work together, or at least have been designed to a certain abstract standard. Imagine building a car but rather than being able to order Ford-fitted parts or Toyota-fitted parts, you'd just get generic parts that you then have to machine yourself in order to make work. Every part, every screw, everything. It'd take tens times as long as if you only had to machine rare parts (e.g. a 1965 engine block to fit a 1973 model frame).