LPM, careful hygiene when preparing formula powder and bottles reduces the gastro risk because you are shutting off one possible way for bugs to enter the digestive tract, but this is only part of the story.There is no evidence that it can be 'completely avoided' with scrupulous hygiene, and in any case, breastfed babies get gastro as well, just not as frequently overall. So it's just not possible - or even desirable - for babies to avoid all infection.
The other two common infant conditions which have been studied in relation to feeding western and indeed UK infants are ear and chest infections. The three conditions feature in a number of cohort studies from the UK and elsewhere in the West.
The reason young babies are especially affected by their diet is because their growth, metabolism and their immune system and their whole physiology is developing, in a way and at a rate that never happens ever again in their life, and milk is their sole nutrition. So to say 'they're going to have loads of formula milk after the age of six months, anyway, so how important can that be?' is not right.
None of this is to say all ff babies are gonna get ill, shock horror, and it's a terrible thing to give a baby formula - it's not a terrible thing at all! But I think it should be perfectly possible to acknowledge that how a baby is fed makes a difference, especially as we understand how the infection thing works, without this evidence being dismissed.
I don't understand your outrage about research into infant feeding and obesity. Clearly, the way a baby is fed is only one element of the social, behavioural, cultural, psychological, emotional, physical phenomenon of obesity. But given that there some plausible connections with early infant diet, it makes sense to me to explore this more fully. Recent research indicates that it may only be certain babies whose risk of obesity is reduced, principally those babies who are already at risk because of other family factors pediatrics.aappublications.org/content/early/2014/11/25/peds.2014-1392.abstract. Other babies' development of obesity is unaffected, maybe.