SPAs might be the right approach for specific applications that are actually applications (e.g. text editors, Jupyter notebooks, chat and other web apps) but more generally the web is designed from the ground up to work well with separate pages representing separate resources.
Each keypress would direct you to a new URL derived from a hash of the new text, an approach that takes advantage of browser history to provide a built-in undo function. Fans of this “content-addressable text editor” say it reminds them that writing is ultimately a grand exploration of Borges’ Library of Babel.
SPAs might be the right approach for specific applications that are actually applications (e.g. text editors, Jupyter notebooks, chat and other web apps) but more generally the web is designed from the ground up to work well with separate pages representing separate resources.