The problem honestly is your concept of hormones is incomplete. There are no hormones that only do one thing. They might have a primary function. But they all have secondary and tertiary functions. They all regulate other hormones. Evolution doesn’t do single functions.

If you knock down a “fight” hormone you’re probably going to mess up the homeostasis of the body in other ways. You can probably “fix” that artificially, but you’ll be constantly chasing the next side effect. Humans are chemical Rube Goldberg machines of infinite order. Disrupt one thing and it all goes out of whack.