Answer 1

Not sure what you mean? All of us here are learning to code or already know how, so I guess the answer is nothing?

If you mean people that aren't coders and don't have an interest in it, then that's like asking what's holding all of us back from being surgeons? We don't want to be surgeons so we don't learn how to be.

Most people are happy simply using software and they've no need to know how it all works. Just like for most people, they just need their car to run when they turn it on and drive when they push the peddle. They don't need to know how it works under the hood to happily use it, and most of them aren't mechanics.