Whats the deal with ARFID?

Fully prepared to get shot down but here goes

How is ARFID not just an excuse for poor parenting? Like if your kids a fussy eater, you don't just accept it and let them eat what they want at the expense of a healthy balanced diet with fruit and vegetables. This sounds to me what ARFID essentially is. How is it a biological medical condition

Say next week, a paediatrian describes a syndrome and called it "Will only eat Big Mac disorder" or "WOEBMD", will we just say to parents, and patients, its ok, eat nothing but Big Macs, you have WOEBMD, you are victim of a recognised medical condition. We can't push you to eat anything else. Don't bother showing tenancity, resilience and hard work offering other foods

See what I mean?