So what exactly is the point of the restriction if you could just put Empower, Enlighten or Enhance into the actual weapon (or body armor in the case of the amulet)?
Or am I missing something here?
edit: forgot about the +2 gems and possible corruptions
The exceptional supports are fundamentally different from other supports - they modify the skill gem, not the skill it grants you - and thus have a different implementation than standard supports. The way they work relies on being physically linked, and as such we weren't able to make them work with this mechanic.