The usefulness of any theory is in its ability to make accurate predictions.
Isolated groups of species like Australia and oceanic islands are a case in point.
If evolution were real, and there were no arbitrary creator populating isolated oceanic islands (think Hawaii and the thousands of scattered Pacific islands that were never part of any larger land mass), then you would expect certain patterns of plants/animals, i.e. nothing that could not conceivedly fly/float to such an island.
A creator would feel free to place big, heavy trees, animals, and amphibians like frogs on such islands. Large trees tend to have larger seeds, think walnuts for example, that don't travel well over ocean currents. Similarly, your average large ape or antelope ain't gonna swim a few hundred miles.
That would leave plants with small seeds, birds that could fly, and small critters that might float around on jetsam for a while.
Care to guess what kind of pattern of creatures you find on these oceanic islands?
(remember, palm "trees" aren't actually trees)