What "benefits etc" do you think blueberries offer?
They're a great source of vitamins and antioxidants and a health snack. But they're not a supplement and not needed. And they certainly don't aid in weight loss in any way if that's what someone is trying to sell you.
Generally, to those who say "just eat blueberries", supplements offer a condensed version of whatever the benefit is. Eg for raspberry ketones you would have to eat pounds and pounds of raspberries to get anywhere near the amount of ketones in just one pill. So every day you'd eat almost nothing but raspberries. Who wants to do that?
Now, I agree, who wants to use raspberry ketones anyway? They're a scam. But they illustrate the principle.
If there is some benefit a blueberry supplement might offer, it may not be accessible simply by eating a small handful of blueberries daily.
Deb, in New Zealand