Skeletal Meshes load unused textures into memory from hard referenced assets. (Skeleton, Physics Assets)

Physics Assets & Skeletons referenced by the skeletal mesh will load materials & textures from their default skeletal meshes into the statistics window. Either the statistics window is incorrect about which textures are actually loaded, or the Statistics window is correct and we are loading textures that are not used.

This was reported and tested in 4.22.1 (CL-6063286). This was reproduced in 4.21.2 (CL-4753647) and Main 4.23 (CL-6191074)

1. Open the UE4 Editor and create a new Third Person project
2. Create an Empty level
3. Navigate to the Mannequin>Character>Mesh folder
4. Drag the SK_Mannequin into the Editor and click on Window>Statics
5. In the Statistics window select the first dropdown and select Texture Stats
6. Notice the texture references and delete the SK_Mannequin
7. Create a duplicate of SK_Mannequin and assign different textures and materials to it.
8. Drag it in to the Editor and view the Texture stats on it, might need to click Refresh

Results: Observe that the textures from the first skeletal mesh are present, despite only the second skeletal mesh existing in the scene.

Expected: Only textures that are used by the materials assigned to the skeletal mesh in the scene should loaded. The skeleton's default skeletal mesh & physics assets do not need to load materials & textures.