I don't disagree with anything in particular here, but other developers might fall into a trap with:

  we are not fully enumerating and reasoning about failure cases.

This might put (or keep) a developer in the mindset that they can code a series of imperative instructions to build their minimal viable product, and then come back and tighten things up later.

I expend all my effort in avoiding 'doing two things'. It's bloody difficult, but since I've come around to thinking that recovering from 1-of-2-things-failing is probably impossible in most situations, doing it the bloody difficult way is easier.