What’s an example of the need for a rapid security response ?

From About Rapid Security Responses for iOS, iPadOS, and macOS - Apple Support

- Rapid Security Responses are a new type of software release for iPhone, iPad, and Mac. They deliver important security improvements between software updates — for example, improvements to the Safari web browser, the WebKit framework stack, or other critical system libraries. They may also be used to mitigate some security issues more quickly, such as issues that might have been exploited or reported to exist "in the wild."

If a critical security loophole is discovered, Apple my issue a RSR so this is addressed as soon as possible instead of just including it in a regular update which may also include less urgent things such as new emojis.

The link on top of this page which you had visited, before posting this question here, is shown under the "Related Article” that may have given you an answer.

You need to mention which part of the article or the example given was not clear to you.

With the limited information that you have provided, It is hard to even guess the problems faced by you. 

You may get faster and better responses to your query by --> Writing an effective Apple Support Commun… - Apple ...

Please re-post with detail so that someone else can help.