When sharing blog content across multiple platforms the content is important in total, not just a summary. A summary can be used in some applications, but if you have multiple sites and wish to syndicate articles this is a powerful option. There are many CMS that incorporate this into their platforms and with a simple checkbox your RSS feed can contain the entire content of the story, including images. The formatting or rich text is not required as the code carries the elements in the html and the format of the site that it travels to follows that and matches the formatting based on its design and format. I have used this for over 10 years with multitudes of clients and we just experienced a client with Webflow who did not realize it was not an option. I say give the customers the option, it is their content. Do not restrict their use to just a summary.