Kinda late, but I thought that there are typically corrective measures that try to prevent oncogenes from kicking off. The key difference between "accumulated lightning bolts" and the final model chosen is that "accumulated lightning bolts" assumes a more or less fixed rates of lightning bolts, while the final model essentially that the rate of lightning bolts will increase over time, which corresponds well to an interpretation of long-term decay of corrective measures - such as replication error detection systems.

I think the key point is that systems for retaining homeostasis (so second order systems I guess) are themselves subject to degradation.