I think you are right, the problem was the 'debate' was so polarised and spiteful and the potential outcomes became likewise. Everyone in our parliament was claiming they were after a reasonable deal, but I believe it came down to one side trying to get the hardest brexit possible, and the other being duplicitous and seeking to stop it altogether. May probably did her best to get a decent compromise, but fell foul of the old adage about trying to please everyone and ending up pleasing no one. Boris jumped in stuck his fat finger in the wind and guessed he could 'get it done' etc.
I do recall options like EFTA being on the table in 2016, but in the end I think the EU understandably got the hump.