When and why did online surveys remove the back button?!

I did 2 customer surveys in the last days and for both they only had a forward button (or even worse: auto forwarding on selecting a choice), but no back button.

Why would you remove that? That's so stupid. Especially with touch screen the answer given might have been by accident. Why would you not give people the chance to give you correct answers??

It was standard to have back buttons last time I did such a survey.