Here's the thing though...
Article 50 only sets out the leaving process. What happens afterwards and any terms etc cannot be begun until the A50 bit is done. This is why there has to be the transition phase to thrash out any long term items such as trade/customs etc deals/details.
The backstop is what will happen if the transition period fails to reach agreement to all the details. This is why it is so vague. Until March 29th and the end of A50, none of these details can be formally addressed.
The second, smaller document submitted yesterday is a prelude to the final arrangements which will form the basis of post transition... ie our ultimate place as a separate entity to the EU.
A hard/no deal Brexit is the most simplistic of alternatives with everything set by WTO rules and hard borders. This could yet happen at one of two points...
1. On March 29th if the EU fails to unanimously sign off on yesterday's submission; or...
2. At the end of the transition period if there's no progress with the details outlined within yesterday's submission and, significantly, both UK and EU agree that it would be better than invoking the Backstop.
Brexit could never realistically be a simple line in the sand. It is, in fact, a long drawn out process that we are about a third of the way through...
Whilst it's not a great foundation for a long-term deal, yesterday's submission is about as good as it gets as far as getting the A50 process signed off
