Why they couldn't have spent the last two years working on a no deal with the EU, laying the ground for our full participation with the WTO, whilst simultaneously ironing out leaving difficulties and having a joint UK/EU agreement as to how we would go forward (because the EU doesn't want to lose it's trade with the UK either).
It would have been a much better use of time.
If May had said to Barnier and Juncker from the beginning, two years ago, "We are leaving - how do you want to trade with US in the future?" it might have been a better strategy, leaving us in almost the same place we are now, but without any of the ground work laid for an alternative plan.
I cannot imagine though, that there hasn't been a Plan B which kicks in if we cannot agree terms with the EU. We will continue to trade with the EU in the future anyway. They need our market too.. I think we have tried too hard to be conciliatory.
Back to square one maybe, after two fruitless, bitter years?