You want to strictly preserve your methods when it comes down to laying bricks and mortar. You rarely want to change anything. But when it comes to decorating the house – that’s when it pays off to be creative, because changes to decoration are not 'mission critical'. They can make the difference between a more attractive house and a less attractive one but they are not mission critical and will not make or break the ability to survive (when going back to the organism which is the metaphor of this example). That’s why secondary metabolite enzymes have an advantage by being promiscuous (or
“creative” to use the language of our metaphor). Plants are normally not lucky enough to be in a static environment. The insects and the animals, if the not the environment itself around them – are constantly changing. So it is beneficial for a plant to say, biosynthesize the pheromones of the predators of its herbivore attackers. But those pheromones keep changing and the pests keep changing. So the plant wants to, basically, change its “bag of tricks” as often as it can. “Whatever works” survives better. But when you shut off the promiscuity of that biosynthetic activity, you basically shut off development. Which guarantees that the plant will be outsmarted or outcompeted by its would-be predators, two, three or perhaps eight generations down the line.
All that said, I don’t think it is worth our while to spend too much time convincing ourselves that this is going to work, or too much time pondering whether it will work or not. Human Assisted Mycosynthesis has already been demonstrated, and fungi are much less promiscous then plants. The main path to discovery here is a curiosity driven, inspiration driven process. It must be planned and tried and when it leads to discoveries that actually work – we have something. So, I think it makes sense to discuss Efraim Lewinsohn’s aromatic melons, it makes sense to talk about the metabolism of carbamazepine in Israeli toxicity from Israeli vegetable irrigation – because there is literature showing that this phenomenon occurs in plants that have been watered with an external unnatural molecule which has been added to their feed. Additionally, there’s a very small body of literature, which talks about something called silent metabolism, which is the capability of plants to do things that nobody (including them) knew they could.