Hi Jolyon.
No, I wasn't saying a story point is a proxy of time.
I think quite the opposite as is clear in the article.
A spring however is a unit of time. Usually two weeks.
While may well be a correct way to think of points and an incorrect way to think of points, what I, you or anyone thinks doesn't matter because there will be people who say. "We burned 18 points last sprint, why have we only burned 15 this sprint". That is, in my view, an inaccurate and wrong thing to say.
So why continue using a medium that's so easily misconstrued? It doesn't make sense.
I can travel the world like a missionary and endeavour to tell the whole world about the mistakes they're making or I can simply swap out numbers for letters. I think the latter is more pragmatic.