My quest was to get an album folder name that contained disambiguation data and specific data for FLAC and MP3/AAC. Beets needed to parse different format related fields for each of them.
You might ask why you would want this info in your folder name (it could be consided as clutter) but I find it very useful to be visually able to determine which albums could use an upgrade from e.g. mp3 --> FLAC or from FLAC 16-44 to 24-96.