> could have backed out of this disaster in a politically acceptable way

I don't think any retreat would have ever been politically acceptable. The general public saw through the "hard/soft" Brexit angle, it was clear that remaining in the single market would not have delivered the majority of leavers wishes.

Worse still, this heavy push on "soft Brexit" made the perception that certain sections of the establishment was trying to deceive their way out of the vote stronger. This sort of feeling, that outside powers are pursuing objectives against our wishes, was a strong driver in the ref vote.