No amount of encouragement or training will make a baby develop the muscle strength or coordination to do things they are not able to do. It's highly likely that a rational person would recognize this after a small number of failures.
Most people don't place babies in harm's way. I've never seen anyone trying to train an infant to roll over, sit up straight, or to raise it's head up off the floor. If that sounds silly, it's because it is. Infants can't do what they can't do. And they will not stand idly by if you're forcing them to stand before they're ready. They will slump, and likely cry.
People have been raising babies for millennia, and doctors rarely see injuries or conditions caused by this manner of overeager parents.* Having a baby sit up early (allowing the legs to straddle properly) or to walk with assistance is fine; often the babies love and want to do this. They are eager to see and explore their world. Again, doing this (e.g. walking with assistance) will not happen if the baby hasn't already sent some time pushing himself into a standing position on the parent's lap.
Most parents want their child to succeed. Placing something continually out of their baby's reach is frustrating, and most people don't do this intentionally. If the baby tries and fails, parents will often adjust their expectations.
The idea that you can encourage a baby to do something before it is developmentally ready to is foreign to me.
*Having said this, children's bones and joints are different than those of adults. The most common unintentional injury inflicted on a child by overeager parents is a condition called nursemaid's elbow or radial head subluxation. This is not uncommon when a child is yanked by their arm when unwilling to follow an adult (hence the name nursemaid's elbow). It's often also caused in an attempt by a parent to save a child from falling by holding onto the child's hand (an understandable maneuver and usually done reflexively), less commonly by rough play and swinging a child by their arms. Gentle traction doesn't cause this. Lifting a very young child by the hands or arms might. It is good to note that there is no similar injury to the knee, hip, or shoulder. Bones do break more easily in young children. Falling on an outstretched arm can result in collar bone fractures. These are usually not readily preventable. Children love to run.
Baby’s First Year: How Infants Develop