I always found it funny that companies will go to extreme Herculean lengths to hire the best programmers, and are incredibly fearful and paranoid that they could be making a "bad hire", and yet once hired they don't spend a second making sure engineers aren't completely running the software product off the rails and killing the company internally. The author mentions trying to rewrite Etsy's backend in Scala and Mong…
But more often than not, this feedback comes from engineers that a) have never been (as you say) bitten by complexity, or b) they aren't in the position to deal with all the negative consequences for those decisions.
There's probably some wisdom in letting your direct reports experience the kinds of failure in making these decisions, so they develop that sort of empathy, but the cost of that failure is sometimes just unacceptable for the business; especially in periods of cash runway constraints.