The Shocking Secret About Static Types (2016)

Reducing bug density is not the main value of static typing as the article states. It vaguely recognizes other values, ending with static types being overrated for reducing bugs.

The famous marketing rhetoric is “large-scale web applications are hard without static types”. It’s true that static types power some really great developer tools such as jump to definition and automatic refactoring, and those tools feel like they make us more productive. (And may actually make us more productive, we need more study on the real benefits of static types).

Productivity is what it's about. And if you have increated productivity then you may have the same rate of bugs per delivered feature, you have more bugs delivered per unit time which is a nonsensical metric. The main thing is you have more featured delivered per unit time.

Not as clickbait as the headline might lead you to believe.

TL;DR: The evidence is that static types reduce bugs, but not as much as you might expect. Test-driven development (per studies) does more to reduce bug count. But static types are good for enabling tools that can help you program better.