WordPress is a free and open-source CMS written in PHP, Initially released in 2003.
I have worked on more than 50 WordPress projects, and find it really easy to get started, especially if you're a small organization or can’t afford the proper development time of creating an application from scratch.
I don't understand why people hate WordPress so much. Few devs advise others to leave the WordPress website as it is not scalable, and has security issues (You are not suppose to use nulled plugins or theme).
People want to build their application on React in the influence that it is the only way to make it fast, and for that they have to adapt a latest framework on Python or Node.js or PHP, but Why do they want to redevelop the backend when It is available in WordPress by default?
My point here is not that WordPress is best and everyone should use it, but don't switch from WordPress under the impression that it is not scalable. especially when you already have an application built on WordPress, and you can totally have a Frontend on React or Next.js and Backend or admin panel on WordPress.
WordPress has functionality of REST api by Default no matter what kind of application you have, you can create its rest api endpoint, Also there are great plugins which can help you to have GraphQL endpoints and your frontend can be any JS framework.
Following are a few of my favorite open source git repo for headless wordpress, built on latest frameworks
Here I am not promoting it, Just want to understand if there is a real need to switch backend as well? when these features are available in WordPress and even easier to develop it.