The browser does not render or understand SASS code. Thus serving such files for the sake of styling not only is not required but it doesn't even work¹.
¹ Well, yeah, it can work—there're many SASS implementation, including a JavaScript one that can be used in a browser.
The SASS code you see in your browser's developer tools (not just Chrome) is a developer tool. In order to diagnose CSS issues you can instruct your SASS compiler to generate source maps. A source map is a document that links positions in your possibly minified CSS files to the SASS source code it comes from. When you open your developer tools and the CSS file declares a source map (example):
/*!
* Bootstrap v4.1.3 (https://getbootstrap.com/)
* Copyright 2011-2018 The Bootstrap Authors
* Copyright 2011-2018 Twitter, Inc.
* Licensed under MIT (https://github.com/twbs/bootstrap/blob/master/LICENSE)
*/:root{--blue:#007bff;--indigo:#6610f2;--purple:#6f[…]
/*# sourceMappingURL=bootstrap.min.css.map */
… the browser downloads the map (example) which in turn links the corresponding SASS source code files.
{"version":3,"sources":["../../scss/bootstrap.scss","../../scss/_root.scss","../../scss/_reboot.scss"[…]
Together with the file/line/column mapping information, developer tools can reconstruct the SASS code where a given element styles come from.
"mappings":"AAAA;;;;;ACAA,MAGI,OAAA,QAAA,SAAA,QAAA,SAAA,QAAA,[…]
The source files are obviously not required. Whether to include them or not depends on factors like:
Is it okay to distribute them or they contain stuff that's meant to remain private like internal comments or intellectual property?
Do you need to diagnose stuff in the live site?
