Generated mapping should have centered Origin like Automatic Texture Space but it uses Lower Left Corner.

When creating multiple decals/splat maps/stickers for Web3D/gLTF you often want to use the Generated texture mapping coordinates as textures can be replaced in realtime however this mapping style uses a lower left corner origin when in the shader tree so scaling a generated mapped texture is not very intuitive. This is at odds with Blender generated meshes (data -> Texture space) which will use a centered origin of the mesh bounding volume.

Not only that but the texture can not be flipped using a mapping node with -X scale as the image input for decals usually uses "Clip" to avoid tiling and as the auto created origin is in the lower left corner, the flipped mapping would be outside the bounding volume so the texture vanishes.