Currently, creators are able to bypass UGC avatar bundle validations in Studio and break avatar guidelines by inserting incredibly small polygons in their body parts. This can lead to the spread of avatar bundles that are not standardized for experiences (e.g. quadruped avatars, inaccurate hitboxes, obscurity).
The advanced avatar auto-setup is able to solve this by deleting the loose geometry upon generating an avatar so that the validation is able to detect it.
However, manual creation of avatars is still able to get around it and pass validation.
If Roblox is able to address this issue, it would prevent the spread of exploitable avatars.