I agree that that's the best way to take these kind of "rules", but that's the opposite of how the blog author presents it:

> the 3-30-300 test — a standard that has become the go-to for solving a universal urban problem

> 3-30-300 is a catchy, straightforward test that sets a clear benchmark for measuring equal access to nature.

> I found that my closest park isn't 300 metres away, it's 400 metres. That's close, but a fail.

It's a standard. It's a benchmark. And a park at 400 metres is no good; it must be 300 metres or else it may as well be 4 kilometers away. This isn't treating the test as a useful guidance, but as a hard target. As Goodheart's law states: when a measure becomes a target, it ceases to be a good measure.

When you focus exclusively on satisfying such metrics, you can end up with ineffective policy. Missing the forest for the trees, if you will.