Awesome question/post!
I have pondered this after an extremely pro-BF friend of mine practically "broke up" with me because she did not perceive that I put forth enough effort to BF my firstborn. I had a breast reduction when I was 20, and was warned that my ability to make milk was going to be challenged, and the surgeon who performed the reduction also informed me that for someone with such large breasts, I had so few glands that production would probably be an issue for me regardless. (my mom, her mom, my aunts, etc. were all LOW producers--my mom was raised on goat's milk in Mexico, my grandmother was wet nursed by her father's sister!!) Anyways, back to my friend...
I met with LLL consultants, the lactation nurses at the hospital, volunteers, rented a hospital grade pump, took fenugreek, pumped 100 minutes+ per day, drank quarts of water, ate well, etc. EVERYTHING I could to increase production. After 6 weeks, I had a miserable baby (who figured out where the milk was coming from on the SNS tube), I was depressed, and my husband practically thought having a child was a huge mistake. My friend kept telling me that she just KNEW I could do it, she called me daily--or more than once a day, brought me books, sent me links to videos to watch online, and kept reminding me that BF was the BEST way to raise my baby. She knew how hard it was, she exclusively BF her 3 kids because formula is poison, blah, blah, blah... Talk about me feeling like a miserable failure! My husband finally had to start fielding the calls and tell her that I was trying my hardest and "thank you" for your concerns.
When I finally decided enough was enough, and went to formula exclusively-- what a change for our family! We slept, we smiled, we enjoyed each other! My friend expressed her disappointment with me for not "sticking it out" or at least continuing pumping.
I tried so hard to understand why she wanted me to continue torturing myself. I think it came from how hard it was for her, yet she was able to do it; and for me to "throw in the towel" was like taking the easy way out. I also think perhaps to some degree she was "jealous" (for lack of a better word), that I wasn't going to be continuing with the physically demanding sacrifice that breastfeeding IS. It is nice to not worry about what I'm going to eat, to take any med I may need if I get sick, if that glass of wine or pint of beer means I need to pump-n-dump, that my husband can help with night feedings, etc.... But that's not the reason I stopped. Although, I have friends who have told me how liberated being able to give formula once in a while makes them feel.
Personally, I have heard from some friends/relatives/professionals in the field and they aren't all "breast is best" folks. Being a formula kid myself, and now having two extremely healthy, bright, active, delightful daughters... I feel kind of sad that I let myself feel so terrible! Another friend of mine who is a LLL volunteer said the "dirty little secret" of a lot of pro-BF women is that they do supplement with formula. She told me that one of the lactation nurses at the hospital she visited frequently was so nasty to women who knew they wouldn't be BFing, and when she had a baby and realized how extremely challenging it was to BF and work full-time, she pretended to pump at work but was actually formula feeding her child exclusively.
I think the worst story I heard was of breast cancer survivor who had a double mastectomy that was in the formula aisle of her grocery store and was berated by a woman for not nursing her child (this woman had been through hell and back in order to use her own eggs to have a baby after her cancer treatment)... Horrible. We don't know each other's circumstances and to automatically assume that our own values are what's best for everyone else is immature.
...Oh, and by the way, I teach 13 year olds and cannot tell you who was BF and who was formula fed, so any statistic that says formula fed kids are "less intelligent" or "less healthy" is showing a tiny, tiny, difference statistically speaking! And what about women who BF exclusively, and then let their children eat junk/processed/fast food, where are all the judgmental folks there?