The section called "Fat and Flour" in the second article I cited goes into that exact issue. It isn't just a matter of the type of fat you use, but also how you mix it with the flour. Here's an excerpt (but the whole section is informative):
It’s not just the chunks of fat that create flakiness. It’s also the uncoated flour that mixes with water and forms gluten that guarantees a flaky crust. This explained the failure of the test in which I combined all the flour with some of the butter, then added grated butter to the dough. You need at least some flour that hasn’t been coated with butter in the dough in order to create the gluten layers that form flakes.