The ability for users to add blocks to their own profiles has been unavailable for the past few versions, due to what was previously a bug. But now the removal of the ability completely is up for discussion. Because it has been unavailable since 2.4 and there were no bug reports or attention outside of us at HQ it seems like it would be safe to remove the feature.
Does anyone know a use case for the feature, or a reason to keep it? If so we can fix the bug making it unavailable.
For more info, feel free to read issue to remove the feature MDL-51067, or the issue to fix the bug MDL-37736 (closed but can be reopened later)