My point in posting my experience is that everyone is different, and people who say, "just do X and it will solve all your problems," have very little likelihood of being accurate. I'm glad your father is doing well, but trust me, I have a host of unavoidable, congenital issues that I have to deal with. Many, many people have other sorts of congenital issues which will make going barefoot painful.

you probably have some kind of problem with the fascia at the bottom of your foot

Nope. The pain is primarily around the edge of the heel. It's hard to explain, but definitely not tendon or ligament pain.