The thing is, people basically give up a full year.
Yeah for the first couple of weeks/first month you're knackered and glued to the sofa anyway. But at about 6 weeks you start getting very bored and restless. And the adrenaline has worn off and you start to get very very tired of basically being a milking machine. If you haven't introduced bottles by then you're starting to close the cage around yourself just when you start to get antsy.
And not all people can just "pop the baby in a sling and BF on the go". Some babies loathe slings, and some women (like me) have such an oversupply that BFing in public is a messy and humiliating business. At least at home nobody notices your top has suddenly become sodden. And if you've an oversupply you're generally encouraged to BF lying down anyway. For ALL feeds. Until it magically sorts itself out. (In my case, it never ever did)
So if you get through all that and have a baby who never did take a bottle, or who you forgot to train on a bottle, then it'll be a year or so of whipping your boob out 24/7. (Cos god forbid they go back to sleep without it.)
Or longer. I remember my friend wailing to me that she genuinely had thought they just "naturally stopped" after a year. She ended up BFing till 3 and those last two years almost killed her. She had a strong willed child and had missed her window. Once the child was a toddler, it was game over till the child decided otherwise.
I BF myself and would do it again, but I'm bloody glad I introduced bottles of expressed early on, and I'm bloody glad I stopped after they started weaning . I feel like it was the best of both worlds both for them and for my mental health.