It’s not the support, it’s the wear of the sole. They don’t wear down evenly and can eventually negatively affect how you walk and cause issues. Even if you wear flat barefoot shoes. Like usually the inside part of the heel will wear down faster if they are worn down too much it can cause pronation or supination issues in some people.

You do understand that people have different feet right? You being a flatfoot doesn't mean others are

I broke my left arm 25 years ago. And it's still broken today.

Healing bones is a perpetual cycle. You need that arm because you've lived with it, it made your limbs weak.