One Page Is Not Enough
Having just a single page means that complex websites that would typically consist of multiple pages (e.g., an online shop with pages for products, orders, and more) become quite difficult to build with React. Without multiple pages, you have to fall back to state and conditional values to display different content on the screen.
But without changing URL paths, your website visitors can't share links to anything but the starting page of your website. Also, any conditionally loaded content will be lost when a new visitor visits that starting page. That will also be the case if users simply reload the page they're currently on. A reload fetches a new version of the page, and so any state (and therefore user interface) changes are lost.
For these reasons, you absolutely need a way of including multiple pages (with different URL paths) in a single React app for most React websites. Thanks to modern browser features and a highly popular third-party...