I disagree.

> [...] vs something that's rickety

A 100 percent of modern bridges are rickety. There has been dozens of high profile incidents because of this.

> Just because you built something that might fall apart at any moment doesn't mean it's been engineered with narrow tolerances.

Here the software they are building falls apart in ..say.. two days of use, but can be updated in 5 seconds at close to zero marginal cost. The software is useful enough that people keep updating and using it. This iteration gives them a competitive advantage over the safer choice of rigorously testing every new thing for several weeks.