It was an impossible task because nobody ever defined what 'leave' meant. Years were spent arguing over whether it meant 'no deal' or varying degrees of some deal. Leavers were undecided in what leave meant. Some leavers would have voted remain if the option was a hard Brexit. We also had arguments over whether MPs should support their constituents or the "will of the people". I remember asking people that, if Brexit would guarantee significant job losses in a constituency, what should the local MP support?
Remain only had 1 option - remain. Leave had many different options. The leave campaign should have spelt out from the start what Brexit was going to mean, rather than leave and sort things out afterwards. The leave campaign wouldn't accept that as it would have definitely lost them the referendum.