sometimes with “complex” scenes. you might see later that things are attached as one object.
while you want them too detach them, too give them another material.
Or sometimes you just want to upload, add an object too the scene instead of uploading the whole fbx all together. escpecially if the fbx whole scene is big in data size.
Or the uv tilling isnt just right. maybe add new uwv coordinates depending on size of the object?
or you want too move/delete an object in the scene.
You can go back in to your 3d program and try too fix it.
But maybe a handy feature is to add/replace small fbx objects, so you can prop your scene with objects.
maybe a faster/different workflow, then uploading a big sometimes static fbx.
then go back and forward between the two programs.
because there is a difference how you see the things in your 3d program and in the 3d sketchfab renderer
offcourse these are just suggestions.