Real user monitoring is a crucial for IT operations and application support in order to ensure their website visitors have a good experience. With the right tool, you can track the entire experience of your website visitors from the user’s click into the browser. If a user experiences a problem, you must be able to identify the loading state in which it occurred. For example, was it a network issue, backend server, or in the browser.
Looking at the states can reveal information about the performance of your site.For example, are the various states of the loading process getting faster or slower? Perhaps there is a sudden change in a particular one, or a long-term change in multiple ones.In any case, Real User monitoring will indicate where you should start looking for the cause of the change
You can read more here: Understanding loading states in real user monitoring