One positive attribute of dietary fat that It's a good source of?

Your question doesn't make much sense to me but I am guessing you are asking what is a positive aspect of dietary fat so I will pretend like that's what you asked. Dietary fat is "good" for you because it is an excellent source of nutrients including fat soluble vitamins and it is packed with calories. You need a certain amount of calories. Fat calories are not any better or worse than sugar calories and IMHO I think they are better actually, so there you have it.