Framework are great, they provide a set of tools so that we can focus on building the product we want faster. A key point for SEO is page loading time, which means every ressources the app downloads should be indispensable. By using a framework, it won't be the case. You never use 100% of what is provided, but nevertheless, the final app bundle will have unused code. We can improve that by overriding default configuration files to only include what's needed in our app. For Ionic, this guide is a good first step.