Who told you that? Better how? React and other frameworks are worse, more complicated, useless and slow. This is how modern society with whole marketing is manipulated.
People see that "speedup" in case of those "frameworks" only because they have 0 knowledge in software engineering and architecture and can't build an app themselves, they need nanny to tell them what folders and files to create and where to put them. Whenever I teach web development, I always start from the basics of software engineering and architecture and showing different ways building software from scratch.
The only use-case scenario I see is learning for beginners, so there would be some examples for them on how to structure app, what is a N-tier architecture, what is a component-based architecture, what is MVC / MVVM etc.
Nothing is better then the only and mighty 3 pillars of the Web - HTML, CSS and JavaScript (and always and only in that direct order, many people forgot that also and start directly from JS and doing a huge mistake)
Eric Hodonsky