fear of formula

La
I've noticed that a lot of breastfeeding moms on here have a fear of formula. I breastfed for a month but was never able to produce enough to sustain my son so right off the bat I was okay with the idea of formula. I told myself going into it that I'd do the best I could, I wouldn't stress myself out over it and whatever happened happened. So I just don't understand this fear of formula. 
Example: one mom was EBF for 6 months and her mother In law gave her daughter formula and she absolutely lost it. She said she cried and sobbed and was so livid at her MIL that she wasn't allowed to see the baby anymore. 
Another mom EBF (not sure for how long) and she started drying up at a certain point and just absolutely refused to supplement with formula. She really acted like she believed it was poison. I have no idea if she ended up supplementing or if she got her supply back. But the post I saw implied she refused to supplement. 
So, without making other moms feel like crap about themselves, if you have a fear of formula, please explain why you're afraid of it... please provide evidence. 
Btw, this isn't a breast is best debate so just stop it before you even go there. There are plenty of breastfeeding moms who will supplement without losing their minds and they believe breast is best. This is about people who believe 4 ounces of formula will somehow hurt their child.