He was more "don't worry, we'll fix that on the mix".
I have this 'teach yourself guitar' book that I use now and again. It has an interesting segment in the back about studio etiquette and things you should do and don't do - and one of the 'DOs' is "consider shooting anyone who says 'I'll fix it in the mix'". And I agree. You want everything going to tape/disc exactly as it should be, or as close as is humanly possible.