I suspect it's mainly due to the intuitiveness of folder-based file management. It provides a sense of location since a file can only be found on one path, which mirrors the physical world.
Ritt can tag arbitrary files too. I like TagSpaces, but I don't think modifying the user's files, either by renaming or sidecar files, is the best approach. Ritt handles tagging purely by linking to the tagged files and so is completely non-perturbative.
Thanks for the question. There is no need to export your data outside of Ritt since it simply manages your files by linking to them at their current location. Your files are not touched or moved during the tagging process.