Nursing is nearly a full time job. When I was doing it with a six month old via pumping, I tracked my hours spent one week and came up with 30 hours. With another baby, I was nursing in the evenings when home from work, and it was literally 3-4 hours a night. Every night. And often almost a full hour in the morning before work. It varies from baby to baby, but it's a brutal time commitment.
Also, when you're nursing full time, you can't leave the baby. Ever. Getting a haircut requires significant planning because if the baby gets hungry, it is your problem and yours alone. If you want to go shopping or see a movie or just leave the dang house for any reason at all, if you want to do any activity that occupies you for a length of time and is hard to interrupt, you need a baby plan. And for a period of months, when in love with a newborn, this seems totally fine and totally worth it. But somewhere on the road to a year? Being able to hand a baby to someone to watch for an hour or two and go do things is amazing.
Don't get me wrong, nursing is a wonderful experience and very important for the health of mother and baby. But the value diminishes over time. With a preemie, it is downright lifesaving. With a newborn it has proven lifelong benefits. But somewhere around the time they're eating cheerios and licking the floor and snacking on apple juice, and you have other things to do, you ask yourself if it's really worth what it costs. At least, I did.
Where you come down on the value of breastfeeding vs formula really depends a lot on your life circumstances and the relative priorities you place on mothering via milk, and mothering via other activities. When and where you leave off is very personal. Some women want to nurse toddlers, and I support that. Some women want to use formula from day one, and I'm not crazy about that, but life is varied and sometimes circumstances dictate and when they do, I'm glad we have the option. In particular, I think this is really common after a C-section, which makes sense -- mom is recovering from surgery and breastfeeding can involve resting a baby on a recovering wound! I'd certainly never second guess someone who thought it more important to have the energy to be emotionally present with the baby, even if that meant feeding baby a different food than they'd wish for in a perfect world. Milk has its benefits, but having an emotionally healthy mom counts for a lot, too. Probably more. And it's a long journey. Trying too hard to do everything perfect can result in mental health issues for mom, which isn't good for anyone, baby included.
Some women transition early, and I support that, some do late, and I support that, too. All parents try to do right by their children, and for some that looks like laborious custom homemade food and for some that looks like neighborhoods and education and opportunities. I do think we'd be better off as a society if it were more practical to nurse for the first year--I think a lot of women would choose it if it were easier. But that involves understanding it like the full time commitment it is. Can I put a year of "full time mom" on my resume? Three times? Can I take a year off of work? Is spending a year nursing seen as a normal and honorable career choice? That's essentially the ask. Whether the gap is made up by state or society or family or whatever, the world would have to look pretty different for me to find it a practical option to make such a commitment to nursing that formula was entirely unnecessary. For some people it's that important. Some would like to, but it's too hard. Some people aren't cut out to be full time moms. And sometimes even full time moms think it's better to use their energy for other things.