Good question! Hypothesis tests come into play when the stakes are high, and if the data makes it hard to tell. If you have data that make the issue abundantly clear and implementing the wrong solutions would not cause anyone harm then you probably don’t need the added proof of hypothesis tests.
Black Belts are required to use them in their projects when they are working toward certification because it’s a learning exercise. Their projects may not truly require hypothesis testing, but they need to know how to select and run tests in case they need them for future projects.