But isn't this in many ways actually even more risky?
When Parliament gets its vote, the two year exit period will almost certainly be almost over and a vote of Parliament will not be able to stop the exit. Instead it will be a vote on the new arrangements with the EU. So either they just have to rubberstamp whatever gets put to them or - if they vote down these new arrangements - Britain will be left outside of the EU without any new deal in place.