Disclaimer before the rant, I breastfed for 8 months with the odd bottle of formula and then FF from 8-12 months. So, anyone who think I have a weird projection going on because I don’t agree with them can stop right there 
I don’t think formula ‘undermines breastfeeding’, it has saved many many many more lives than it has damaged. It is already illegal to advertise formula for use before the age of 1. How can you ‘undermine breastfeeding’ anyway? It doesn’t have feelings, it isn’t a person 
The fact is breastfeeding, while it has a small benefit which means it’s the NHS encouraged method, simply doesn’t have the incredible properties that mean it is worth spending £££ promoting it. There is zero noticeable difference between a breastfed child and non-breastfed child, you can only see the effect if you look at hundreds of thousands of children. And even then it doesn’t protect completely against any
one thing.
I think mumsnet has a strange cognitive dissonance in which it believe in freedom of feeding choice on paper but in reality wants formula to be a dirty word, hidden from view in case it ‘undermines breastfeeding’. If you trust women to make the right decision for them, then they should have the information on both methods (with stats, not just talk of ‘amazing health benefits’ which turn out to be a slightly lesser chance of an ear infection).
I also once saw a poster on here who genuinely believed her child didn’t need the MMR as she was breastfeeding and ‘I had measles therefore
my child will be immune through my milk’. When another poster pointed out the measles antibodies have no effect after the first 2-3 months of feeding the poster never came back to the thread 😬