CSS preprocessors like Sass and Less provide several benefits, such as making CSS more maintainable, themeable, and extendable. They allow for the use of variables, mixins, and advanced features, which improve organization and save time. Additionally, they contain fewer codes, so you can write CSS more quickly. On the downside, preprocessors require installation, and Sass, in particular, needs to be compiled into CSS. Some developers are also reluctant to adopt preprocessors, leading to potential compatibility issues. Additionally, Less doesn't support functions like Sass. Despite these drawbacks, many big companies, including Uber and Airbnb, use preprocessors like Sass and Less to improve their CSS workflow.