I think little of zeal outside of close-knit groups. It takes too much effort, it's easily misdirected, and it can be faked. At scale, it incurs a deficit between input and output, willpower and reality, and eventually achieves its close cousin and exact opposite, cynicism. In the world after zeal, trying becomes pretending, enthusiasm becomes opportunism; anything done the cause becomes suspect in the eyes of those who had to suffer the cause.

The inability to control zeal seems common to communist republics[1], "rocket-ship" startups, and other half-baked endeavors that don't know how to get work done without demanding religious fervor/perfection from their unfortunate subordinates.

[1] https://en.wikipedia.org/wiki/New_Soviet_man -> https://en.wikipedia.org/wiki/Homo_Sovieticus