It depends on how you use SASS. Used correctly, with @extend rather than @include for big swatches of styles that reoccur in multiple places, it will be DRY and

It depends on how you use SASS. Used correctly, with @extend rather than @include for big swatches of styles that reoccur in multiple places, it will be DRY and light. Your designer colleague probably didn't have a sufficient understanding of the difference between @extend and @include. It's not hard though, a few tests using the different methods and analyzing the results should be enough to understand when to use each. It is utterly impossible to generate worse CSS with SASS than by just writing CSS directly, as SASS does not deprive you of any CSS feature. SASS provides you with a bigger and more capable toolbox, but won't stop you from using the wrong tool in any given situation.