At 40% failure rate, the keyboard would be useless as a keyboard. What would you use it for?! 40% means the backspace, delete key wouldn't work 40% of the time, and even might hit the enter key instead.
Trying to fix the mistakes, would lead to more mistakes! Which I guess is apt, because that sounds a lot like AI.
You could use the keyboard to prop a door open though.
Is it 40% failure per individual back/forth or 40% failure per individual letter output? I guess it really just depends how much one wants to bash AI instead of actually talk about failure rate not normally being what makes using a tool worthwhile :D.
I'm not big on AI for much more than additional "Google search" type usage myself so it's interesting to see how polarized folks are that LLMs either have to be the greatest gift from god to take over the world or completely 100% useless trash which couldn't ever be used for anything because the output is not always correct.