Well, if they want to then that's a legitimate reason.
Not, it seems, in and of itself. Women who say "I wanted to breastfeed because I think it's the best nutrition for my baby" get screamed down that by saying that they're denigrating formula and formula feeding mums, that the evidence is weak, that they're wrong to want to on that basis basically. Women who say "I wanted to breastfeed because I think it will enhance my bond with the baby" Get screamed at that how dare they imply a ff mum's bond with her baby isn't EXACTLY THE SAME as a bf mum's. Women who say they find it convenient get a barrage of comments saying that it isn't convenient, that it's painful and dangerous and exhausting, that formula is very convenient, that it allows others to help etc etc.
Personally, I was desperate to breastfeed and struggled through a lot of challenges in the early months to do so because I had a horrible birth ending with an epidural and an EMCS, in which I felt utterly let down by my body and separated from my baby, and breastfeeding felt, to me, at the time, the best way to repair that psychological damage and rebuild that physical bond which felt like it had skipped a step by missing out on the experience of birthing. But when I share this POV, I have had some sympathetic responses, but also a barrage of criticism for - simply be feeling these feelings about my body, my birth, and my baby - criticising all women who had c-sections and all women who don't breastfeed. My reasons, however deeply personal, are treated as invalid, and critical of others.
I am still breastfeeding my 18 month old. In her whole life, this fact has never arisen when I am with a formula feeding mum (and when I say 'arisen', I don't mean I start banging on about it, I mean I start feeding my daughter - or these days, she clambers onto me and feeds herself!) without that mum going on the defensive, starting to tell me her reasons for not breastfeeding, and starting to denigrate the evidence base for breastfeeding promotion.
I never speak to my NCT group about any parenting or relationship issues I am having without half the women in the group immediately attributing my troubles to my continued breastfeeding, however irrelevant to feeding the issue is.
Never EVER would I or have I ever done similar to them and implied their children's sleep, health, or behavioural issues are down to formula. Because apparently that would be me pissing on them from my position of incredible power as a bf mum 