As a #software #engineer, try to go your whole #career without building anything which will cause millions of #users to spend frustrated hours searching for a way to turn the damn thing off.
Notable #failures to adhere to this principle: #Google's "#AI" #search summaries, #Microsoft's conversion of #Windows into an #advertising billboard that happens to sometimes show an #application window, "#smart" appliances/devices that can't perform their basic function without #phoning the #mothership.
But that's only the first recent 3 examples that came to mind, and I ran out of space.
I'm sure users (and engineers!) in the #Fedi have all kinds of other examples they could add here...