Why is a fat transfer recommended for doing my lower blepharoplasty? And what will happen if I don’t include that procedure?

The doctor I am considering recommends transconjunctival blepharoplasty with skin pinch and a fat transfer, under local anaesthesia, for my particular case. He says this will avoid the chances of ectropion (is that true?). However, I have read a lot of mixed information, opinions, and results about doing fat transfers under the eye - some say it’s great, some say it’s a bad idea. Why so much mixed info? And is a fat transfer best performed at the same time as a lower blepharoplasty?