"A fish can't whistle and neither can I." There's nothing wrong with not being able to whistle, especially if you're a fish.
But there can be lots of things wrong with blindly trying to do what you aren't designed for. Unfortunately, some people aren't so wise, and end up causing big trouble for themselves and others. The wise know their limitations; the foolish do not.
To demonstrate what we mean, we can think of no one better than Tigger, who doesn't know his limitations ('Tiggers' can do everything'), which brings him in lots of trouble.
Perhaps it isn't all about being just an uncarved block of wood, perhaps it is having a little wisdom and being not so wise as to try things we can not do, or aren't designed to do, like whistle like a fish. Perhaps.