The ESRB has always been a system exclusively designed to benefit the games industry rather than to give a single iota of a damn about the consumers. As someone who used to work retail many years ago (and had friends/siblings who did the same), very few parents bother to even look at ratings or content descriptors at all. They buy whatever their kid wants them to buy.
The Target mom who bought her 5 year old son Grand Theft Auto 3. I will never forget that sale lol.