You're trying to reason with someone who has no children but knows more about taking care of them than any parent here.
I also had 5 kids, all breastfed on demand, per doctor's advice.
Been there, done that.
It sure is easier than putting them on a schedule, isn't it?
I had friends who had very fussy babies on THEIR schedules. ONe finally fed the baby on demand and what a happy baby!
Who'da thunk?