I could believe that their test rig didn't adequately simulate the motions/stresses of finger keypresses.
Uh, the butterfly isn't used in Apple keyboards anymore. They reverted to the old scissor switch design some time ago.
It would have been much better if they had figured out how to cut their losses and revert the keyboards in 2016 or early 2017, even though that would have taken a substantial redesign of the rest of the laptop internals.
Selling 4.5 years of laptops with keyboards that broke easily under ordinary use was a huge black eye for the company.
Given that Apple is still selling, or has only just stopped selling models with the latest butterfly keyboard - the issue may have solution, but hasn't gone away. Millions of laptops have faulty keyboards which, when they break, will be replaced with another faulty keyboard. That's an unresolved issue.
To be fair to the designers, the height budget they were working with is an extremely hard target to hit for a part that gets as much physical abuse as a keyboard. I was pretty impressed with how passable the keyboard was for typing on, given the height constraint. (However, I was not impressed with the dropped actuations, double actuations, inconsistent key feel after a few months use, broken keycap that my 1-year-old keeps removing and hiding around the house, etc. Overall it ended up being a catastrophically bad design based on poor reliability.)
The biggest problem at company scale was that they couldn't revert to something like their previous keyboard in a shorter time frame. The lesson is to avoid completely locking the whole rest of the system design around a brand new untested part for which there is no alternative. It would have been better to test the new keyboard design in a context like an external iPad keyboard where if it turned out to be a dud there would be an obvious path to an alternative, and customers wouldn't be left with a broken $2000 machine.