This is complete nonsense. Yes, formula has effects that breastmilk does not, and does negate some brestmilk benefits, but nonetheless any breastmilk your dd gets gives her the benefits of breastmilk. And also gives you the benefits of producing bm. (There are health benefits to the mother.)
I was pushed into bottlefeeding my first, but I felt awful about it so kept giving him breast first, then a bottle. According to the can of formula, he was taking full formula feeds on top of whatever bm he got from me. At 6w I had had enough, and decided to try and relactate. If you want to know more, just ask - I shan't push it on you.
Each of my three was bigger than the previous. No3 was 11 lb. I was worried how I would feed him, but, thankfully, had my previous experiences and Marvelous Mumsnet to support me. We had a rocky start, but, as with no2, I succeeded in fully breastfeeding him. He is still a big, solid boy.
All of mine have had some formula. Two have had mostly breastmilk. All are healthy, intelligent, well-grown, and fit.
And I know that I have done my body some good by breastfeeding. There is a history of breast problems in my family. By breastfeeding my dc I have given myself some protection aginst breast problems.