Short answer: maintainability, performance, cross-browser consistency, community plugins, easier developer on-boarding, and framework updates and maintenance (which amplifies most of the previous).
Obviously a lot depends on the complexity of the website, but for the most part, any web _application_ will be better served by a framework. Heck, most static sites can now be amplified by layering on frameworks if done correctly (ie GatsbyJs).
Obviously a lot depends on the complexity of the website, but for the most part, any web _application_ will be better served by a framework. Heck, most static sites can now be amplified by layering on frameworks if done correctly (ie GatsbyJs).