An asset browser allowed you to perform queries (e.g. show me all the characters from level X which reference materials which reference texture Y). We had tags/labels, comments, everything you could want.
When you do it like this your folder organization becomes irrelevant. You can store everything in a single directory with a GUID for a filename if you want. Or store all textures in one place and all 3d models in another. The down side is it's quite opaque, everything must be done within your toolset, so you need great tool support.