Claims

If you want to create the best pizza (the Santa Monica Flying Pizza), the trial-and-error approach is to rent a bus, find well-dressed overweight people (as a proxy for people who understand good food), have them iteratively add ingredients, lock in gains when something tastes good, and incur minimal loss when something doesn't work.

In trial-and-error, the downside is minimal (you simply don't adopt something that doesn't work) while the upside is maximal (discovering something genuinely good), but a chemist's top-down approach trades off limited upside for potential massive downside if the theory-based approach fails.