A leader parent is an involved parent. Every Eagle Scout I’ve known has had a parent/guardian at their side supporting, encouraging, motivating them along the path to Eagle. Doesn’t have to be a registered parent as a leader, but a parent that cares enough to see that they succeed. Involved parents are not just leaders, but the parents that check on their kids status, talk to leaders, ask questions, and make sure requirements are being met.
The parents that just dump their kids off often have no clue what their Scout is doing or how well they’re doing. Some probably couldn’t tell you what rank their kid is. When parents don’t care, the Scout won’t care. Often times they are only there for socialization with friends.