That is actually false. While a typical NFL playbook is quite thick, that is due to a good portion of the playbook covering such things as terminology and blocking schemes.
As far as actual plays go Madden has it relatively accurate. Where it is weak is that it is static. A real playbook evolves and changes over the course of a season, sometimes even on a week to week basis.
When it comes to actual passing plays there are a limited number of route combinations a team can use. The truth is that most of the NFL teams are running the same plays. The differences lie in tendencies and personnel groupings.
Your suggestion that a realistic NFL playbook would be too much for a Madden gamer is not true. So long as they understand how to use the concepts and a good understanding of the strategy behind it.