This might be the only valid reason. But only for website that have a huge amount of traffic.
And only the first visit.
Re:What CSS minifiers also leave behind
by remy_luisant on Wednesday April 05, 2017 @04:48PM
(#14045483)
Unless you are inlining your CSS.
True, the difference between 10KB compressed and 7KB minified+compressed is negligible for your visitors, but it still takes 30% off of your traffic bill.