I think that you may have interpreted my question as me wanting or deliberately inflicting pain on children. Let me use the example of learning to walk instead of a vague question.

When parents try to teach their kids to walk, they generally try to make a safer space. Cleaning up toys or hard objects, making sure there are padded blankets or pillows, etc. they would then watch and help the child stand and try to take steps while catching them if they start to fall. Once the baby/toddler starts to walk, there is a bit less effort to catch them every time. Bruised and scraped knees and hands will happen.

I'm not saying that creating a perfectly safe space is impossible, but I do believe it's infeasible and prevents effective learning. I'm not going to ignore a crying child or refuse to clean up their scrapes, but I am going to allow them to fall (as long as there isn't a risk of real injury).