As a person who runs a small software business, coding most of the functionality myself, I actually disagree with the article. There is a huge value in setting deadlines because they force you to prioritize things. Once you realize that you don't have the time to ship features X, Y and Z, you start comparing their impact/complexity/risks, pick the most beneficial one, and ship it before it's too late.

Without prioritization it's very easy to get stuck in a loop of endlessly adding small improvements/testing new ideas, but never releasing the final sellable product. There are a few notorious examples from the game industry where no time pressure lead to either no product, or a hopelessly late-to-market product (e.g. Half-Life 3, Duke Nukem Forever). There are more smaller examples where entire teams endlessly juggle the code between web frameworks, as they come in and out of fashion, and neglect more user-impacting features.

That said, most of time pressure should only be applied at the decision-making level. Once you have decided to ship feature X with framework Y, it's useless to nag on your devs to do it in half the time by dropping unit tests, or doing 60-hour work weeks. Instead, you should have picked feature Z with 50% the complexity and 80% user impact.