obviously the actual weight matters, but on average this advice is poor.
Across the spectrum of over weight people (from mildly to extremely obese) there are a range of health markers from blood pressure, HDL/LDL/Triglycerides, insulin sensitivity, leptin/ghrelin, sex hormones (and PE/ED), blood sugar, cortisol, inflammation, arterial calcification (on and on the list goes) that are all positively improved by returning to healthy "normal" (not average) weights.
Layne Norton's book "Fat Loss forever" and youtube channel are excellent resources to begin understanding.
https://www.youtube.com/watch?v=XUxVCtScf8U
https://www.goodreads.com/en/book/show/43596925-fat-loss-for...
Not least because weight loss is unlikely to make someone much healthier unless they have type 2 diabetes, severe hypertension, or are way beyond "overweight". There is a substantial population-level association between obesity and morbidity, but it's heavily influenced by those who are extremely obese (which tends to come with a variety of other issues not immediately relevant to the average fat person).