While I agree every start-up should be able to summarise their business in a single sentence, this isn't always possible. As the article points out it can encourage the use of vague buzzwords tip-toeing around the actual workings of the company and leaving people still without a clue as to what the company actually does.

And sometimes a business simply can't be summarised to such a short length, after all you want the listener to gain a quick, yet good understanding of what your start-up does. Keeping it short could lead to leaving out critical information though.

That said, I'll certainly work on single sentence descriptions for my projects, it can only be a credit to your business if you can have the listener instantly know what you do in a matter of seconds.