In Steves situation, as I understand it, the eggs were getting hard, which is not the optimal situation for a baby ball python to be able to slit the egg by its self. Lack of humidity, etc can cause problems with the egg shell, which may cause the baby to be unable to emerge, ergo drowning in its own egg.
Exactly. The humidity was bad thruout incubation and the shells were very hard. I had a hard time with a razor sharp surgical scalpel getting thru them. I doubt an egg tooth would have been able to break thru.