Frameworks make decisions for you about how to organize, structure, and design a site. Pattern libraries don’t separate styling and markup, making them tough to use in a truly modular fashion. They weren’t satisfied, so they made a thing that doesn’t do that.

Typeplate is a “typographic starter kit”. They don’t make aesthetic design choices but define proper markup with extensible styling for common typographic patterns. A stripped-down Sass or CSS library of your choosing is primarily concerned with the appropriate technical implementation of design patterns—not how they look.