With regard to babies being able to have a cup, or resisting a bottle not being serious enough to delay going back to work....I would challenge both.
Babies need to be fed, clearly. It is not possible to return to work if a baby will not feed. Some women find trying to give a bottle, or a cup is SO resisted and rejected, that they feel it will never work (who knows I'd it would eventually..but time is often not on their side) so don't return to work.
With cups, many women find baby will take a tiny amount, but not the quantities needed for a full tummy.
I am not saying that because of this, everyone should mixed feed, simply that one of the benefits of mixed feeding is this problem is avoided.
Regarding the idea that just one bottle means breast feeding will end sooner.....this may well be true, but is put in a way that gives people that terrible guilt they get over formula or mixed feeding. It maybe true....well so what, if it means breastfeeding ends a bit sooner, if the net benefit for the whole family makes it worth it.
And I find that even when NCT people or other advisors are advising, in a so-called open way, which says everyone has choices and mixed or formula feeding might be the best thing for an individual, it is said in such a way, as to make clear that this is an INFERIOR option. There is never really a suggestion that in this particular situation and for this particular family, it might be best. I understand breast is best. However, I think we really do need to recognise what we are aiming for is the best outcome for that family. The baby is well served by being healthy and having a family who are in a good place to parent them. This might not be best provided by ebf in every situation, but mixed might be better. I think this message needs to come across.
I understand there had been a mass move away from breast feeding altogether and amongst certain groups that still occurs. I understand that the breast is best message needs to go out. However, for many groups, they have a sense that ebf is not for people like them, so they never try. If they thought they could do both, they just might try it.
So overall, we need to aim for the best outcome for a whole family. Baby is part of the family and whilst ebf is best for their health, baby will be best served by having parents in a good place. And people saying they didn't find ebf inconvenient or tying or painful or tiring, or not providing enough milk, does not help. Because lots of people who do mixed feeding DO find these problems with ebf and are not wrong because of it.