I agree with Hunkermunker.
I also think it comes down often to how convinced different people are by the scientific stuff re breastfeeding.
If you think there's not much more benefit from breastfeeding than from formula, then I'd guess you're probably more likely to interpret almost any encouragement, help, advice re breastfeeding as evangelical zeal, rabidity, whatever. You're more likely to see 'rabid pro-bfers' on every corner.
At the other extreme, if you're sincerely convinced that the difference between breastfeeding and formula is big enough that many people who end up formula feeding (those who might have been able to avoid it with better support and info as opposed to those with insurmountable physiological or circumstantial probs, say) should consider themselves seriously let down by health professionals, conned by the industry's undermining of breastfeeding support etc., then what others see as rabidity you're far more likely to see as simple basic honest support and information.
How often does the scientific stuff actually get debated? Not often I think - everyone says they agree breast is best but actually how best they see it as varies loads between different people. Maybe if that debate was thrashed out first then there'd be fewer people arguing past each other about whether a particular way of talking about breast or formula constitutes rabidity, chippyness or whatever. A comment that seems blindingly obviously 'rabid' to one person (with one opinion of how 'best' breast is), is equally blindingly obviously 'normal encouragement' to someone else with a different opinion of how 'best' it is. In a way they may both be right about the comment - the real debate is in the underlying assumptions.