Eons ago, an ancient demigod was imprisoned by a group of his siblings within a separate realm for crimes against humanity. A cult of witches in the modern day has formed to free this individual, and operates as a shadow government behind the world's institutions. The cult is responsible for the majority of world events that have led to mass death. The purpose of instigating these events is to destroy a magical ward separating our world from the realm of this demigod, which is made up of seven seals which holds reality together and keeps it from shattering.
Each seal is built with increasing complexity. The first seal requires a simple mass genocide to be broken, while A violent act of murder releases a backlash of negative energy in our reality. Steps become increasingly complicated with each seal, requiring rises and falls of various empires, solar eclipses, etc. With each breaking of a ward, the ward becomes weaker until it completely cracks, allowing the Outer God to enter our dimension.
When designing a firewall, the purpose is to keep any outsider from penetrating the system in order to protect its contents. Any weak points are vulnerabilities that can lead to a security breach, giving a hacker increasing access to the inside. This allows an intruder more time to learn and adapt, providing them with more opportunities to enter further. It would be sensible to design a single seal with herculean tasks meant to keep intruders out rather than seven with different degrees of complexity. Or alternatively, make each seal equally as challenging as possible, instead of slowly building up the difficulty with a natural progression.
What would be the benefit of doing it this way?