It isn't even necessarily about changing your mind, it's about misclicking. It's like filling in the wrong bubble of a Scantron form and the answer automatically being sent as soon as you put the pencil on paper. It shouldn't be making those assumptions until you verify that's the response you want to send. On multiple occasions I've clicked a radio button in a form thinking it was the most relevant to me before reading the rest of them (which is not really relevant to this poll in particular, but how the interaction should be treated regardless).

But I definitely agree the responses should not be visible until you've voted.