I am not a doctor or licensed physiotherapist.

In general, shoes can compress the toes together which distorts one's literal footprint. This causes the great toe to bend inward enough to partially or even fully collapse the arch. People that are barefoot most of the time do not have this problem, and their great toe is in line with the bones behind it. Basically since it's not a thumb, it's really not supposed to be bent inward.

We also do goofy things like walk with heel strikes instead of on our toes when using shoes. It's why some runners have a bad time with shin splints and require shoes with a ton of heel padding - you're really not built to do that.

Do Shoes Alter the Form and Function of Your Feet?

So called "bunion spacers" and toe spacers help restore proper great toe positioning which in turn can restore the arch. I was diagnosed with fallen arches, and stumbled into this by accident. My PB for deadlift is now 265lbs, and have had zero arch pain or related issues for years. The trick is to purchase a shoe with a wide toe-box to accommodate the wider toe-end of your footprint when wearing the spacers.