It's what unites the scone. The main challenge for making scones is to achieve that crumbliness. It should fall apart easily when you pull a part off, but it shouldn't crumble apart in your hands.

What's the consistency of a scone flaky or crumbly?

A scone should not flake like a biscuit.

It can have layers of course, but they should err on the side of crumbly. A scone is slightly dryer than a biscuit and yet, when done well, not dry at all. Scones are intended to be consumed with a hot beverage of your choice after all. And clotted cream, or butter, or jam.

What texture should scones be?

A good scone should have a “short” crumbly texture, not a tough, bread-y texture. The gluten (a protein in the flour) is developed when it is made wet and worked by kneading.