Well, if you are genuinely discussing the merits of BF vs FF then it seems a bit odd to say that no one should mention the benefits of BF. Because then either you only get to mention the benefits of FF (pretty one-sided) or no one gets to mention the benefits of either (pretty silent).
There is real research supporting almost all of the touted benefits of BF, and it seems unreasonable to avoid mentioning them ever because it might upset someone who didn't have the option. And there's a real justification for talking about things in terms of the drawbacks of FF rather than the benefits of BF -- FF has become normalised to the extent that it's seen as "ooh, you can confer all these extra benefits on your child by breastfeeding" when that's just not the case. Breastfeeding is something women (as a whole) are designed to do. It's something most women are able to do. It's the way babies (as a whole) are designed to be fed. It's not a magic extra thing you can do on top of "normality".
It's like, say, TV watching. Assuming for a moment (as is often suggested) that watching TV under the age of 2 is bad for children, the message isn't "Hey, mothers! If you don't let your under-2-yo child watch television at all then you can improve their lot in the following ways..." but rather "Watching television under the age of 2 may hinder development in the following ways..." No one objects to that. I don't get worked up about it's being negative and unfair to me because I let my DCs watch Cbeebies from very young. I accept that "not watching television" is children's natural state and it's only reasonable to talk about the negative effects of television, rather than the positive effects of no television.
If someone physically can't breastfeed, or can't exclusively breastfeed, then the small disadvantages that her child may, statistically, receive from being fed formula rather than being fed breastmilk are clearly massively outweighed by the huge advantage that the same child receives from being fed rather than not fed. Even if someone physically can breastfeed but doesn't for [whatever reason] it's entirely possible that the small disadvantages that her child may, statistically, receive from being fed formula are outweighed by some other benefits stemming from her choice. It doesn't mean that there aren't, statistically, disadvantages to being fed formula. It doesn't mean that formula is as good as breastmilk. But it does affect whether someone should devote huge amounts of time to feeling bad about it after the event.
To use the television analogy again, I am quite prepared to accept that the statistics suggest that there may have been some small disadvantages to my children because I sat them in front of Cbeebies, but I am happy that those were outweighed for our family by the overall benefits to family wellbeing that I feel we got from it. I may be right or wrong about that; it may be that I would have done something differently under different circumstances, or with the benefit of some study that will come out in ten years' time.
It would be plainly daft for someone to suggest that letting an 18-month-old watch half an hour of In The Night Garden was automatically knocking off 20 IQ points and adding 5 points to his or her eventual adult BMI. I have encountered some posters who do imply that by FF, or by weaning a child at 5 months rather than 6, you are massively increasing the chances of all sorts of negative outcomes when the "massively" bit really isn't supported by evidence.
I think maybe we get more worked up about breastfeeding, and less able to accept that we have accepted some risks of negative impacts, because it's our own bodies involved? Or perhaps because it's about what is actually going into our children's bodies and physically making them up? Everything certainly seems to be taken far more personally for some reason.