Here and here is a very nice summary of all that is wrong with Butterfly keyboard.
April 2015: Apple Inc. releases the all-new MacBook with a “butterfly” keyboard. In order to achieve extreme thinness, the keys are much flatter than older generations but the butterfly mechanism underneath, for which the keyboard is named, aims to replicate the bounce of a more traditional keyboard.
October 2016: The MacBook Pro arrives with a second-generation butterfly keyboard. A few months later, some begin to report that letters or characters don’t appear, that keys get stuck or that letters unexpectedly repeat.
And this came out last week:
This is bad and demonstrates a company with massively inflated ego.