I think there is a lot of shaming of formula mums. A small amount of ffers saying they feel that way could be chalked up to the usual 'you just feel guilty' but there is a pretty universal mentality (especially on line with formula bashing is rife) there has to be something to that. So while the actual concept isn't hidden the choice to ff is fraught with value judgments. And telling women they are too swayed/easily manipulated/too vulnerable to be able to make an educated decision can really make some women feel alienated.
Even now I'm bristling at the idea that somehow I'm free to live my life and trusted to make informed decisions about a plethora of things but I'm not able to pick a formula without being tricked into it.